Merge branch 'master' into dependabot/composer/vimeo/psalm-4.6.1

31 files changed, 1152 insertions, 85 deletions

diff --git a/lib/Command/CreateAccount.php b/lib/Command/CreateAccount.php
index 61c32b454..a1b95a283 100644
--- a/lib/Command/CreateAccount.php
+++ b/lib/Command/CreateAccount.php
@@ -25,6 +25,7 @@ namespace OCA\Mail\Command;
 
 use OCA\Mail\Db\MailAccount;
 use OCA\Mail\Service\AccountService;
+use OCP\IUserManager;
 use OCP\Security\ICrypto;
 use Symfony\Component\Console\Command\Command;
 use Symfony\Component\Console\Input\InputArgument;
@@ -52,11 +53,17 @@ class CreateAccount extends Command {
 	/** @var \OCP\Security\ICrypto */
 	private $crypto;
 
-	public function __construct(AccountService $service, ICrypto $crypto) {
+	/** @var IUserManager */
+	private $userManager;
+
+	public function __construct(AccountService $service,
+								ICrypto $crypto,
+								IUserManager $userManager) {
 		parent::__construct();
 
 		$this->accountService = $service;
 		$this->crypto = $crypto;
+		$this->userManager = $userManager;
 	}
 
 	/**
@@ -99,6 +106,11 @@ class CreateAccount extends Command {
 		$smtpUser = $input->getArgument(self::ARGUMENT_SMTP_USER);
 		$smtpPassword = $input->getArgument(self::ARGUMENT_SMTP_PASSWORD);
 
+		if (!$this->userManager->userExists($userId)) {
+			$output->writeln("<error>User $userId does not exist</error>");
+			return 1;
+		}
+
 		$account = new MailAccount();
 		$account->setUserId($userId);
 		$account->setName($name);
diff --git a/lib/Command/DeleteAccount.php b/lib/Command/DeleteAccount.php
new file mode 100644
index 000000000..c32b41fa0
--- /dev/null
+++ b/lib/Command/DeleteAccount.php
@@ -0,0 +1,92 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * @author Anna Larch <anna.larch@nextcloud.com>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+namespace OCA\Mail\Command;
+
+use OCA\Mail\Account;
+use Psr\Log\LoggerInterface;
+use OCA\Mail\Service\AccountService;
+use OCA\Mail\Exception\ClientException;
+use OCP\AppFramework\Db\DoesNotExistException;
+use Symfony\Component\Console\Command\Command;
+use Symfony\Component\Console\Input\InputArgument;
+use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Output\OutputInterface;
+
+class DeleteAccount extends Command {
+	public const ARGUMENT_ACCOUNT_ID = 'account-id';
+
+	/** @var AccountService */
+	private $accountService;
+
+	/** @var LoggerInterface */
+	private $logger;
+
+	public function __construct(AccountService $service,
+								LoggerInterface $logger) {
+		parent::__construct();
+
+		$this->accountService = $service;
+		$this->logger = $logger;
+	}
+
+	/**
+	 * @return void
+	 */
+	protected function configure() {
+		$this->setName('mail:account:delete');
+		$this->setDescription('Delete an IMAP account');
+		$this->addArgument(self::ARGUMENT_ACCOUNT_ID, InputArgument::REQUIRED);
+	}
+
+	protected function execute(InputInterface $input, OutputInterface $output): int {
+		$accountId = (int)$input->getArgument(self::ARGUMENT_ACCOUNT_ID);
+
+		try {
+			$account = $this->accountService->findById($accountId);
+		} catch (DoesNotExistException $e) {
+			$output->writeLn('<error>This account does not exist</error>');
+			return 1;
+		}
+		$output->writeLn("<info>Found account with email: " . $account->getEmail() . "</info>");
+
+		if ($account->getMailAccount()->getProvisioned() === true) {
+			$output->writeLn('<error>This is a provisioned account which can not be deleted from CLI. Use the Provisioning UI instead.</error>');
+			return 2;
+		}
+		$output->writeLn("<info>Deleting " . $account->getEmail() . "</info>");
+		$this->delete($account, $output);
+
+		return 0;
+	}
+
+	private function delete(Account $account, OutputInterface $output): void {
+		$id = $account->getId();
+		try {
+			$this->accountService->deleteByAccountId($account->getId());
+		} catch (ClientException $e) {
+			throw $e;
+		}
+		$output->writeLn("<info>Deleted account $id </info>");
+	}
+}
diff --git a/lib/Contracts/IMailManager.php b/lib/Contracts/IMailManager.php
index ca17c0edf..9b3f48e41 100644
--- a/lib/Contracts/IMailManager.php
+++ b/lib/Contracts/IMailManager.php
@@ -221,4 +221,12 @@ interface IMailManager {
 	 */
 	public function enableMailboxBackgroundSync(Mailbox $mailbox,
 												bool $syncInBackground): Mailbox;
+
+	/**
+	 * @param Account $account
+	 * @param Mailbox $mailbox
+	 * @param Message $message
+	 * @return array
+	 */
+	public function getMailAttachments(Account $account, Mailbox $mailbox, Message $message) : array;
 }
diff --git a/lib/Contracts/ITrustedSenderService.php b/lib/Contracts/ITrustedSenderService.php
index 7f0de8aab..1f25e93d4 100644
--- a/lib/Contracts/ITrustedSenderService.php
+++ b/lib/Contracts/ITrustedSenderService.php
@@ -30,7 +30,7 @@ use OCA\Mail\Db\TrustedSender;
 interface ITrustedSenderService {
 	public function isTrusted(string $uid, string $email): bool;
 
-	public function trust(string $uid, string $email, ?bool $trust = true);
+	public function trust(string $uid, string $email, string $type, ?bool $trust = true);
 
 	/**
 	 * @param string $uid
diff --git a/lib/Controller/AccountsController.php b/lib/Controller/AccountsController.php
index 9c79668e9..be4ba7602 100644
--- a/lib/Controller/AccountsController.php
+++ b/lib/Controller/AccountsController.php
@@ -194,6 +194,13 @@ class AccountsController extends Controller {
 						   string $smtpSslMode = null,
 						   string $smtpUser = null,
 						   string $smtpPassword = null): JSONResponse {
+		try {
+			// Make sure the account actually exists
+			$this->accountService->find($this->currentUserId, $id);
+		} catch (ClientException $e) {
+			return new JSONResponse([], Http::STATUS_BAD_REQUEST);
+		}
+
 		$account = null;
 		$errorMessage = null;
 		try {
diff --git a/lib/Controller/MessagesController.php b/lib/Controller/MessagesController.php
index ad49a8275..6361d415e 100755
--- a/lib/Controller/MessagesController.php
+++ b/lib/Controller/MessagesController.php
@@ -51,6 +51,7 @@ use OCP\AppFramework\Http\ContentSecurityPolicy;
 use OCP\AppFramework\Http\JSONResponse;
 use OCP\AppFramework\Http\Response;
 use OCP\AppFramework\Http\TemplateResponse;
+use OCP\AppFramework\Http\ZipResponse;
 use OCP\Files\Folder;
 use OCP\Files\IMimeTypeDetector;
 use OCP\IL10N;
@@ -527,6 +528,43 @@ class MessagesController extends Controller {
 
 	/**
 	 * @NoAdminRequired
+	 * @NoCSRFRequired
+	 * @TrapError
+	 *
+	 * @param int $id the message id
+	 * @param string $attachmentId
+	 *
+	 * @return ZipResponse|JSONResponse
+	 *
+	 * @throws ClientException
+	 * @throws ServiceException
+	 * @throws DoesNotExistException
+	 */
+	public function downloadAttachments(int $id): Response {
+		try {
+			$message = $this->mailManager->getMessage($this->currentUserId, $id);
+			$mailbox = $this->mailManager->getMailbox($this->currentUserId, $message->getMailboxId());
+			$account = $this->accountService->find($this->currentUserId, $mailbox->getAccountId());
+		} catch (DoesNotExistException $e) {
+			return new JSONResponse([], Http::STATUS_FORBIDDEN);
+		}
+
+		$attachments = $this->mailManager->getMailAttachments($account, $mailbox, $message);
+		$zip = new ZipResponse($this->request, 'attachments');
+
+		foreach ($attachments as $attachment) {
+			$fileName = $attachment['name'];
+			$fh = fopen("php://temp", 'r+');
+			fputs($fh, $attachment['content']);
+			$size = (int)$attachment['size'];
+			rewind($fh);
+			$zip->addResource($fh, $fileName, $size);
+		}
+		return $zip;
+	}
+
+	/**
+	 * @NoAdminRequired
 	 * @TrapError
 	 *
 	 * @param int $id
diff --git a/lib/Controller/SettingsController.php b/lib/Controller/SettingsController.php
index 829068fc2..d65f04f03 100644
--- a/lib/Controller/SettingsController.php
+++ b/lib/Controller/SettingsController.php
@@ -50,7 +50,12 @@ class SettingsController extends Controller {
 								 string $smtpUser,
 								 string $smtpHost,
 								 int $smtpPort,
-								 string $smtpSslMode): JSONResponse {
+								 string $smtpSslMode,
+								 bool $sieveEnabled,
+								 string $sieveUser,
+								 string $sieveHost,
+								 int $sievePort,
+								 string $sieveSslMode): JSONResponse {
 		$this->provisioningManager->newProvisioning(
 			$emailTemplate,
 			$imapUser,
@@ -60,7 +65,12 @@ class SettingsController extends Controller {
 			$smtpUser,
 			$smtpHost,
 			$smtpPort,
-			$smtpSslMode
+			$smtpSslMode,
+			$sieveEnabled,
+			$sieveUser,
+			$sieveHost,
+			$sievePort,
+			$sieveSslMode
 		);
 
 		return new JSONResponse([]);
diff --git a/lib/Controller/SieveController.php b/lib/Controller/SieveController.php
new file mode 100644
index 000000000..11fc5b186
--- /dev/null
+++ b/lib/Controller/SieveController.php
@@ -0,0 +1,219 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * @author Daniel Kesselberg <mail@danielkesselberg.de>
+ *
+ * Mail
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+namespace OCA\Mail\Controller;
+
+use Horde\ManageSieve\Exception as ManagesieveException;
+use OCA\Mail\AppInfo\Application;
+use OCA\Mail\Db\MailAccountMapper;
+use OCA\Mail\Exception\ClientException;
+use OCA\Mail\Exception\CouldNotConnectException;
+use OCA\Mail\Service\AccountService;
+use OCA\Mail\Sieve\SieveClientFactory;
+use OCP\AppFramework\Controller;
+use OCP\AppFramework\Db\DoesNotExistException;
+use OCP\AppFramework\Http\JSONResponse;
+use OCP\IRequest;
+use OCP\Security\ICrypto;
+
+class SieveController extends Controller {
+
+	/** @var AccountService */
+	private $accountService;
+
+	/** @var MailAccountMapper */
+	private $mailAccountMapper;
+
+	/** @var SieveClientFactory */
+	private $sieveClientFactory;
+
+	/** @var string */
+	private $currentUserId;
+
+	/** @var ICrypto */
+	private $crypto;
+
+	/**
+	 * AccountsController constructor.
+	 *
+	 * @param IRequest $request
+	 * @param string $UserId
+	 * @param AccountService $accountService
+	 * @param MailAccountMapper $mailAccountMapper
+	 * @param SieveClientFactory $sieveClientFactory
+	 * @param ICrypto $crypto
+	 */
+	public function __construct(IRequest $request,
+								string $UserId,
+								AccountService $accountService,
+								MailAccountMapper $mailAccountMapper,
+								SieveClientFactory $sieveClientFactory,
+								ICrypto $crypto
+	) {
+		parent::__construct(Application::APP_ID, $request);
+		$this->currentUserId = $UserId;
+		$this->accountService = $accountService;
+		$this->mailAccountMapper = $mailAccountMapper;
+		$this->sieveClientFactory = $sieveClientFactory;
+		$this->crypto = $crypto;
+	}
+
+	/**
+	 * @NoAdminRequired
+	 * @TrapError
+	 *
+	 * @param int $id account id
+	 *
+	 * @return JSONResponse
+	 *
+	 * @throws CouldNotConnectException
+	 * @throws ClientException
+	 */
+	public function getActiveScript(int $id): JSONResponse {
+		$sieve = $this->getClient($id);
+
+		$scriptName = $sieve->getActive();
+		if ($scriptName === null) {
+			$script = '';
+		} else {
+			$script = $sieve->getScript($scriptName);
+		}
+
+		return new JSONResponse([
+			'scriptName' => $scriptName,
+			'script' => $script,
+		]);
+	}
+
+	/**
+	 * @NoAdminRequired
+	 * @TrapError
+	 *
+	 * @param int $id account id
+	 * @param string $script
+	 *
+	 * @return JSONResponse
+	 *
+	 * @throws ClientException
+	 * @throws CouldNotConnectException
+	 * @throws ManagesieveException
+	 */
+	public function updateActiveScript(int $id, string $script): JSONResponse {
+		$sieve = $this->getClient($id);
+
+		$scriptName = $sieve->getActive() ?? 'nextcloud';
+		$sieve->installScript($scriptName, $script, true);
+
+		return new JSONResponse();
+	}
+
+	/**
+	 * @NoAdminRequired
+	 * @TrapError
+	 *
+	 * @param int $id account id
+	 * @param bool $sieveEnabled
+	 * @param string $sieveHost
+	 * @param int $sievePort
+	 * @param string $sieveUser
+	 * @param string $sievePassword
+	 * @param string $sieveSslMode
+	 *
+	 * @return JSONResponse
+	 *
+	 * @throws CouldNotConnectException
+	 * @throws DoesNotExistException
+	 */
+	public function updateAccount(int $id,
+								  bool $sieveEnabled,
+								  string $sieveHost,
+								  int $sievePort,
+								  string $sieveUser,
+								  string $sievePassword,
+								  string $sieveSslMode
+	): JSONResponse {
+		$mailAccount = $this->mailAccountMapper->find($this->currentUserId, $id);
+
+		if ($sieveEnabled === false) {
+			$mailAccount->setSieveEnabled(false);
+			$mailAccount->setSieveHost(null);
+			$mailAccount->setSievePort(null);
+			$mailAccount->setSieveUser(null);
+			$mailAccount->setSievePassword(null);
+			$mailAccount->setSieveSslMode(null);
+
+			$this->mailAccountMapper->save($mailAccount);
+			return new JSONResponse(['sieveEnabled' => $mailAccount->isSieveEnabled()]);
+		}
+
+		if (empty($sieveUser)) {
+			$sieveUser = $mailAccount->getInboundUser();
+		}
+
+		if (empty($sievePassword)) {
+			$sievePassword = $mailAccount->getInboundPassword();
+		} else {
+			$sievePassword = $this->crypto->encrypt($sievePassword);
+		}
+
+		try {
+			$this->sieveClientFactory->createClient($sieveHost, $sievePort, $sieveUser, $sievePassword, $sieveSslMode);
+		} catch (ManagesieveException $e) {
+			throw CouldNotConnectException::create($e, 'ManageSieve', $sieveHost, $sievePort);
+		}
+
+		$mailAccount->setSieveEnabled(true);
+		$mailAccount->setSieveHost($sieveHost);
+		$mailAccount->setSievePort($sievePort);
+		$mailAccount->setSieveUser($mailAccount->getInboundUser() === $sieveUser ? null : $sieveUser);
+		$mailAccount->setSievePassword($mailAccount->getInboundPassword() === $sievePassword ? null : $sievePassword);
+		$mailAccount->setSieveSslMode($sieveSslMode);
+
+		$this->mailAccountMapper->save($mailAccount);
+		return new JSONResponse(['sieveEnabled' => $mailAccount->isSieveEnabled()]);
+	}
+
+	/**
+	 * @param int $id
+	 *
+	 * @return \Horde\ManageSieve
+	 *
+	 * @throws ClientException
+	 * @throws CouldNotConnectException
+	 */
+	protected function getClient(int $id): \Horde\ManageSieve {
+		$account = $this->accountService->find($this->currentUserId, $id);
+
+		if (!$account->getMailAccount()->isSieveEnabled()) {
+			throw new CouldNotConnectException('ManageSieve is disabled.');
+		}
+
+		try {
+			$sieve = $this->sieveClientFactory->getClient($account);
+		} catch (ManagesieveException $e) {
+			throw CouldNotConnectException::create($e, 'ManageSieve', $account->getMailAccount()->getSieveHost(), $account->getMailAccount()->getSievePort());
+		}
+
+		return $sieve;
+	}
+}
diff --git a/lib/Controller/TrustedSendersController.php b/lib/Controller/TrustedSendersController.php
index 552101d8d..54c5d930c 100644
--- a/lib/Controller/TrustedSendersController.php
+++ b/lib/Controller/TrustedSendersController.php
@@ -54,13 +54,14 @@ class TrustedSendersController extends Controller {
 	 * @TrapError
 	 *
 	 * @param string $email
-	 *
+	 * @param string $type
 	 * @return JsonResponse
 	 */
-	public function setTrusted(string $email): JsonResponse {
+	public function setTrusted(string $email, string $type): JsonResponse {
 		$this->trustedSenderService->trust(
 			$this->uid,
-			$email
+			$email,
+			$type
 		);
 
 		return JsonResponse::success(null, Http::STATUS_CREATED);
@@ -71,13 +72,14 @@ class TrustedSendersController extends Controller {
 	 * @TrapError
 	 *
 	 * @param string $email
-	 *
+	 * @param string $type
 	 * @return JsonResponse
 	 */
-	public function removeTrust(string $email): JsonResponse {
+	public function removeTrust(string $email, string $type): JsonResponse {
 		$this->trustedSenderService->trust(
 			$this->uid,
 			$email,
+			$type,
 			false
 		);
 
diff --git a/lib/Db/MailAccount.php b/lib/Db/MailAccount.php
index b5aa8ecae..3df3c1a67 100644
--- a/lib/Db/MailAccount.php
+++ b/lib/Db/MailAccount.php
@@ -77,6 +77,18 @@ use OCP\AppFramework\Db\Entity;
  * @method int|null getSentMailboxId()
  * @method void setTrashMailboxId(?int $id)
  * @method int|null getTrashMailboxId()
+ * @method bool isSieveEnabled()
+ * @method void setSieveEnabled(bool $sieveEnabled)
+ * @method string|null getSieveHost()
+ * @method void setSieveHost(?string $sieveHost)
+ * @method int|null getSievePort()
+ * @method void setSievePort(?int $sievePort)
+ * @method string|null getSieveSslMode()
+ * @method void setSieveSslMode(?string $sieveSslMode)
+ * @method string|null getSieveUser()
+ * @method void setSieveUser(?string $sieveUser)
+ * @method string|null getSievePassword()
+ * @method void setSievePassword(?string $sievePassword)
  */
 class MailAccount extends Entity {
 	protected $userId;
@@ -109,6 +121,19 @@ class MailAccount extends Entity {
 	/** @var int|null */
 	protected $trashMailboxId;
 
+	/** @var bool */
+	protected $sieveEnabled = false;
+	/** @var string|null */
+	protected $sieveHost;
+	/** @var integer|null */
+	protected $sievePort;
+	/** @var string|null */
+	protected $sieveSslMode;
+	/** @var string|null */
+	protected $sieveUser;
+	/** @var string|null */
+	protected $sievePassword;
+
 	/**
 	 * @param array $params
 	 */
@@ -168,6 +193,8 @@ class MailAccount extends Entity {
 		$this->addType('draftsMailboxId', 'integer');
 		$this->addType('sentMailboxId', 'integer');
 		$this->addType('trashMailboxId', 'integer');
+		$this->addType('sieveEnabled', 'boolean');
+		$this->addType('sievePort', 'integer');
 	}
 
 	/**
@@ -192,6 +219,7 @@ class MailAccount extends Entity {
 			'draftsMailboxId' => $this->getDraftsMailboxId(),
 			'sentMailboxId' => $this->getSentMailboxId(),
 			'trashMailboxId' => $this->getTrashMailboxId(),
+			'sieveEnabled' => $this->isSieveEnabled(),
 		];
 
 		if (!is_null($this->getOutboundHost())) {
@@ -201,6 +229,13 @@ class MailAccount extends Entity {
 			$result['smtpSslMode'] = $this->getOutboundSslMode();
 		}
 
+		if ($this->isSieveEnabled()) {
+			$result['sieveHost'] = $this->getSieveHost();
+			$result['sievePort'] = $this->getSievePort();
+			$result['sieveUser'] = $this->getSieveUser();
+			$result['sieveSslMode'] = $this->getSieveSslMode();
+		}
+
 		return $result;
 	}
 }
diff --git a/lib/Db/MessageMapper.php b/lib/Db/MessageMapper.php
index 77ec05776..81f1967a7 100644
--- a/lib/Db/MessageMapper.php
+++ b/lib/Db/MessageMapper.php
@@ -333,6 +333,7 @@ class MessageMapper extends QBMapper {
 			->set('flag_junk', $query->createParameter('flag_junk'))
 			->set('flag_notjunk', $query->createParameter('flag_notjunk'))
 			->set('flag_mdnsent', $query->createParameter('flag_mdnsent'))
+			->set('flag_important', $query->createParameter('flag_important'))
 			->set('updated_at', $query->createNamedParameter($this->timeFactory->getTime()))
 			->where($query->expr()->andX(
 				$query->expr()->eq('uid', $query->createParameter('uid')),
@@ -356,6 +357,7 @@ class MessageMapper extends QBMapper {
 			$query->setParameter('flag_junk', $message->getFlagJunk(), IQueryBuilder::PARAM_BOOL);
 			$query->setParameter('flag_notjunk', $message->getFlagNotjunk(), IQueryBuilder::PARAM_BOOL);
 			$query->setParameter('flag_mdnsent', $message->getFlagMdnsent(), IQueryBuilder::PARAM_BOOL);
+			$query->setParameter('flag_important', $message->getFlagImportant(), IQueryBuilder::PARAM_BOOL);
 
 			$query->execute();
 		}
@@ -433,37 +435,26 @@ class MessageMapper extends QBMapper {
 	public function findThread(Account $account, int $messageId): array {
 		$qb = $this->db->getQueryBuilder();
 		$subQb1 = $this->db->getQueryBuilder();
-		$subQb2 = $this->db->getQueryBuilder();
 
 		$mailboxIdsQuery = $subQb1
 			->select('id')
 			->from('mail_mailboxes')
 			->where($qb->expr()->eq('account_id', $qb->createNamedParameter($account->getId(), IQueryBuilder::PARAM_INT)));
-		$threadRootIdsQuery = $subQb2
-			->select('thread_root_id')
-			->from($this->getTableName())
-			->where(
-				$qb->expr()->eq('id', $qb->createNamedParameter($messageId, IQueryBuilder::PARAM_INT), IQueryBuilder::PARAM_INT)
-			);
 
 		/**
 		 * Select the message with the given ID or any that has the same thread ID
 		 */
 		$selectMessages = $qb
-			->select('*')
-			->from($this->getTableName())
+			->select('m2.*')
+			->from($this->getTableName(), 'm1')
+			->leftJoin('m1', $this->getTableName(), 'm2',  $qb->expr()->eq('m1.thread_root_id', 'm2.thread_root_id'))
 			->where(
-				$qb->expr()->in('mailbox_id', $qb->createFunction($mailboxIdsQuery->getSQL()), IQueryBuilder::PARAM_INT_ARRAY),
-				$qb->expr()->orX(
-					$qb->expr()->eq('id', $qb->createNamedParameter($messageId, IQueryBuilder::PARAM_INT), IQueryBuilder::PARAM_INT),
-					$qb->expr()->andX(
-						$qb->expr()->isNotNull('thread_root_id'),
-						$qb->expr()->in('thread_root_id', $qb->createFunction($threadRootIdsQuery->getSQL()), IQueryBuilder::PARAM_INT_ARRAY)
-					)
-				)
+				$qb->expr()->in('m1.mailbox_id', $qb->createFunction($mailboxIdsQuery->getSQL()), IQueryBuilder::PARAM_INT_ARRAY),
+				$qb->expr()->in('m2.mailbox_id', $qb->createFunction($mailboxIdsQuery->getSQL()), IQueryBuilder::PARAM_INT_ARRAY),
+				$qb->expr()->eq('m1.id', $qb->createNamedParameter($messageId, IQueryBuilder::PARAM_INT), IQueryBuilder::PARAM_INT),
+				$qb->expr()->isNotNull('m1.thread_root_id')
 			)
 			->orderBy('sent_at', 'desc');
-
 		return $this->findRecipients($this->findEntities($selectMessages));
 	}
 
diff --git a/lib/Db/TrustedSender.php b/lib/Db/TrustedSender.php
index d02313f7c..3425c056a 100644
--- a/lib/Db/TrustedSender.php
+++ b/lib/Db/TrustedSender.php
@@ -33,6 +33,8 @@ use OCP\AppFramework\Db\Entity;
  * @method getEmail(): string
  * @method setUserId(string $userId): void
  * @method getUserId(): string
+ * @method setType(string $type): void
+ * @method getType(): string
  */
 class TrustedSender extends Entity implements JsonSerializable {
 
@@ -42,11 +44,15 @@ class TrustedSender extends Entity implements JsonSerializable {
 	/** @var string */
 	protected $userId;
 
+	/** @var string */
+	protected $type;
+
 	public function jsonSerialize() {
 		return [
 			'id' => $this->id,
 			'email' => $this->email,
 			'uid' => $this->userId,
+			'type' => $this->type,
 		];
 	}
 }
diff --git a/lib/Db/TrustedSenderMapper.php b/lib/Db/TrustedSenderMapper.php
index 5d29f224a..b8b8eeae3 100644
--- a/lib/Db/TrustedSenderMapper.php
+++ b/lib/Db/TrustedSenderMapper.php
@@ -34,13 +34,24 @@ class TrustedSenderMapper extends QBMapper {
 	}
 
 	public function exists(string $uid, string $email): bool {
+		$emailObject = new \Horde_Mail_Rfc822_Address($email);
+		$host = $emailObject->host;
 		$qb = $this->db->getQueryBuilder();
 
 		$select = $qb->select('*')
 			->from($this->getTableName())
 			->where(
-				$qb->expr()->eq('user_id', $qb->createNamedParameter($uid)),
-				$qb->expr()->eq('email', $qb->createNamedParameter($email))
+				$qb->expr()->orX(
+					$qb->expr()->andX(
+						$qb->expr()->eq('email', $qb->createNamedParameter($email)),
+						$qb->expr()->eq('type', $qb->createNamedParameter('individual'))
+					),
+					$qb->expr()->andX(
+						$qb->expr()->eq('email', $qb->createNamedParameter($host)),
+						$qb->expr()->eq('type', $qb->createNamedParameter('domain'))
+					)
+				),
+				$qb->expr()->eq('user_id', $qb->createNamedParameter($uid))
 			);
 
 		/** @var TrustedSender[] $rows */
@@ -49,25 +60,27 @@ class TrustedSenderMapper extends QBMapper {
 		return !empty($rows);
 	}
 
-	public function create(string $uid, string $email): void {
+	public function create(string $uid, string $email, string $type): void {
 		$qb = $this->db->getQueryBuilder();
 
 		$insert = $qb->insert($this->getTableName())
 			->values([
 				'user_id' => $qb->createNamedParameter($uid),
 				'email' => $qb->createNamedParameter($email),
+				'type' => $qb->createNamedParameter($type),
 			]);
 
 		$insert->execute();
 	}
 
-	public function remove(string $uid, string $email): void {
+	public function remove(string $uid, string $email, string $type): void {
 		$qb = $this->db->getQueryBuilder();
 
 		$delete = $qb->delete($this->getTableName())
 			->where(
 				$qb->expr()->eq('user_id', $qb->createNamedParameter($uid)),
-				$qb->expr()->eq('email', $qb->createNamedParameter($email))
+				$qb->expr()->eq('email', $qb->createNamedParameter($email)),
+				$qb->expr()->eq('type', $qb->createNamedParameter($type))
 			);
 
 		$delete->execute();
diff --git a/lib/Exception/CouldNotConnectException.php b/lib/Exception/CouldNotConnectException.php
new file mode 100644
index 000000000..c996095ee
--- /dev/null
+++ b/lib/Exception/CouldNotConnectException.php
@@ -0,0 +1,36 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * @author Daniel Kesselberg <mail@danielkesselberg.de>
+ *
+ * Mail
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+namespace OCA\Mail\Exception;
+
+use Throwable;
+
+class CouldNotConnectException extends ServiceException {
+	public static function create(Throwable $exception, string $service, string $host, int $port): self {
+		return new self(
+			"Connection to {$service} at {$host}:{$port} failed. {$exception->getMessage()}",
+			(int)$exception->getCode(),
+			$exception
+		);
+	}
+}
diff --git a/lib/IMAP/FolderMapper.php b/lib/IMAP/FolderMapper.php
index b40d5abeb..f12ea3af8 100644
--- a/lib/IMAP/FolderMapper.php
+++ b/lib/IMAP/FolderMapper.php
@@ -62,12 +62,24 @@ class FolderMapper {
 			'special_use' => true,
 		]);
 
-		return array_filter(array_map(function (array $mailbox) use ($account) {
+		return array_filter(array_map(function (array $mailbox) use ($account, $client) {
 			if (in_array($mailbox['mailbox']->utf8, self::DOVECOT_SIEVE_FOLDERS, true)) {
 				// This is a special folder that must not be shown
 				return null;
 			}
 
+			try {
+				$client->status($mailbox["mailbox"]);
+			} catch (Horde_Imap_Client_Exception $e) {
+				// ignore folders which cause errors on access
+				// (i.e. server-side system I/O errors)
+				if (in_array($e->getCode(), [
+					Horde_Imap_Client_Exception::UNSPECIFIED,
+				], true)) {
+					return null;
+				}
+			}
+
 			return new Folder(
 				$account->getId(),
 				$mailbox['mailbox'],
diff --git a/lib/IMAP/MessageMapper.php b/lib/IMAP/MessageMapper.php
index 96fdb2255..95161fd8a 100644
--- a/lib/IMAP/MessageMapper.php
+++ b/lib/IMAP/MessageMapper.php
@@ -201,11 +201,7 @@ class MessageMapper {
 		$query->flags();
 		$query->uid();
 		$query->imapDate();
-		$query->headers(
-			'references',
-			[
-				'references',
-			],
+		$query->headerText(
 			[
 				'cache' => true,
 				'peek' => true,
@@ -471,28 +467,65 @@ class MessageMapper {
 		}
 
 		$structure = $structureResult->getStructure();
-		$partsQuery = new Horde_Imap_Client_Fetch_Query();
-		$partsQuery->fullText();
-		foreach ($structure->partIterator() as $part) {
+		$partsQuery = $this->buildAttachmentsPartsQuery($structure, $attachmentIds);
+
+		$parts = $client->fetch($mailbox, $partsQuery, [
+			'ids' => new Horde_Imap_Client_Ids([$uid]),
+		]);
+		if (($messageData = $parts->first()) === null) {
+			throw new DoesNotExistException('Message does not exist');
+		}
+
+		$attachments = [];
+		foreach ($structure->partIterator() as $key => $part) {
 			/** @var Horde_Mime_Part $part */
-			if ($part->getMimeId() === '0') {
-				// Ignore message header
-				continue;
-			}
-			if (!empty($attachmentIds) && !in_array($part->getMIMEId(), $attachmentIds, true)) {
-				// We are looking for specific parts only and this is not one of them
+
+			if (!$part->isAttachment()) {
 				continue;
 			}
 
-			$partsQuery->bodyPart($part->getMimeId(), [
-				'peek' => true,
-			]);
-			$partsQuery->mimeHeader($part->getMimeId(), [
-				'peek' => true
+			$stream = $messageData->getBodyPart($key, true);
+			$mimeHeaders = $messageData->getMimeHeader($key, Horde_Imap_Client_Data_Fetch::HEADER_PARSE);
+			if ($enc = $mimeHeaders->getValue('content-transfer-encoding')) {
+				$part->setTransferEncoding($enc);
+			}
+			$part->setContents($stream, [
+				'usestream' => true,
 			]);
-			$partsQuery->bodyPartSize($part->getMimeId());
+			$decoded = $part->getContents();
+
+			$attachments[] = $decoded;
+		}
+		return $attachments;
+	}
+
+	/**
+	 * Get Attachments with size, content and name properties
+	 *
+	 * @param Horde_Imap_Client_Socket $client
+	 * @param string $mailbox
+	 * @param integer $uid
+	 * @param array|null $attachmentIds
+	 * @return array[]
+	 */
+	public function getAttachments(Horde_Imap_Client_Socket $client,
+									string $mailbox,
+									int $uid,
+									?array $attachmentIds = []): array {
+		$messageQuery = new Horde_Imap_Client_Fetch_Query();
+		$messageQuery->structure();
+
+		$result = $client->fetch($mailbox, $messageQuery, [
+			'ids' => new Horde_Imap_Client_Ids([$uid]),
+		]);
+
+		if (($structureResult = $result->first()) === null) {
+			throw new DoesNotExistException('Message does not exist');
 		}
 
+		$structure = $structureResult->getStructure();
+		$partsQuery = $this->buildAttachmentsPartsQuery($structure, $attachmentIds);
+
 		$parts = $client->fetch($mailbox, $partsQuery, [
 			'ids' => new Horde_Imap_Client_Ids([$uid]),
 		]);
@@ -516,14 +549,48 @@ class MessageMapper {
 			$part->setContents($stream, [
 				'usestream' => true,
 			]);
-			$decoded = $part->getContents();
-
-			$attachments[] = $decoded;
+			$attachments[] = [
+				'content' => $part->getContents(),
+				'name' => $part->getName(),
+				'size' => $part->getSize()
+			];
 		}
 		return $attachments;
 	}
 
 	/**
+	 * Build the parts query for attachments
+	 *
+	 * @param $structure
+	 * @param array $attachmentIds
+	 * @return Horde_Imap_Client_Fetch_Query
+	 */
+	private function buildAttachmentsPartsQuery($structure, array $attachmentIds) : Horde_Imap_Client_Fetch_Query {
+		$partsQuery = new Horde_Imap_Client_Fetch_Query();
+		$partsQuery->fullText();
+		foreach ($structure->partIterator() as $part) {
+			/** @var Horde_Mime_Part $part */
+			if ($part->getMimeId() === '0') {
+				// Ignore message header
+				continue;
+			}
+			if (!empty($attachmentIds) && !in_array($part->getMIMEId(), $attachmentIds, true)) {
+				// We are looking for specific parts only and this is not one of them
+				continue;
+			}
+
+			$partsQuery->bodyPart($part->getMimeId(), [
+				'peek' => true,
+			]);
+			$partsQuery->mimeHeader($part->getMimeId(), [
+				'peek' => true
+			]);
+			$partsQuery->bodyPartSize($part->getMimeId());
+		}
+		return $partsQuery;
+	}
+
+	/**
 	 * @param Horde_Imap_Client_Socket $client
 	 * @param int[] $uids
 	 *
diff --git a/lib/Listener/NewMessageClassificationListener.php b/lib/Listener/NewMessageClassificationListener.php
index 365251883..56585730c 100644
--- a/lib/Listener/NewMessageClassificationListener.php
+++ b/lib/Listener/NewMessageClassificationListener.php
@@ -67,11 +67,16 @@ class NewMessageClassificationListener implements IEventListener {
 			}
 		}
 
+		// if the message is already flagged as important, we won't classify it again.
+		$messages = array_filter($event->getMessages(), function ($message) {
+			return ($message->getFlagImportant() === false);
+		});
+
 		try {
 			$predictions = $this->classifier->classifyImportance(
 				$event->getAccount(),
 				$event->getMailbox(),
-				$event->getMessages()
+				$messages
 			);
 
 			foreach ($event->getMessages() as $message) {
diff --git a/lib/Migration/AddSieveToProvisioningConfig.php b/lib/Migration/AddSieveToProvisioningConfig.php
new file mode 100644
index 000000000..e871ff1cc
--- /dev/null
+++ b/lib/Migration/AddSieveToProvisioningConfig.php
@@ -0,0 +1,85 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * @author Daniel Kesselberg <mail@danielkesselberg.de>
+ *
+ * Mail
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+namespace OCA\Mail\Migration;
+
+use OCA\Mail\Service\Provisioning\Config as ProvisioningConfig;
+use OCA\Mail\Service\Provisioning\ConfigMapper as ProvisioningConfigMapper;
+use OCP\IConfig;
+use OCP\Migration\IOutput;
+use OCP\Migration\IRepairStep;
+
+class AddSieveToProvisioningConfig implements IRepairStep {
+
+	/** @var IConfig */
+	private $config;
+
+	/** @var ProvisioningConfigMapper */
+	private $configMapper;
+
+	public function __construct(IConfig $config, ProvisioningConfigMapper $configMapper) {
+		$this->config = $config;
+		$this->configMapper = $configMapper;
+	}
+
+	public function getName(): string {
+		return 'Add sieve defaults to provisioning config';
+	}
+
+	public function run(IOutput $output) {
+		if (!$this->shouldRun()) {
+			return;
+		}
+
+		$config = $this->configMapper->load();
+		if ($config === null) {
+			return;
+		}
+
+		$reflectionClass = new \ReflectionClass(ProvisioningConfig::class);
+		$reflectionProperty = $reflectionClass->getProperty('data');
+
+		$reflectionProperty->setAccessible(true);
+		$data = $reflectionProperty->getValue($config);
+
+		if (!isset($data['sieveEnabled'])) {
+			$data = array_merge($data, [
+				'sieveEnabled' => false,
+				'sieveHost' => '',
+				'sievePort' => 4190,
+				'sieveUser' => '',
+				'sieveSslMode' => 'tls',
+			]);
+		}
+
+		$reflectionProperty->setValue($config, $data);
+		$this->configMapper->save($config);
+
+		$output->info('added sieve defaults to provisioning config');
+	}
+
+	protected function shouldRun(): bool {
+		$appVersion = $this->config->getAppValue('mail', 'installed_version', '0.0.0');
+		return version_compare($appVersion, '1.9.0', '<');
+	}
+}
diff --git a/lib/Migration/Version1090Date20210127160127.php b/lib/Migration/Version1090Date20210127160127.php
new file mode 100644
index 000000000..8a52ae4fc
--- /dev/null
+++ b/lib/Migration/Version1090Date20210127160127.php
@@ -0,0 +1,56 @@
+<?php
+
+declare(strict_types=1);
+
+namespace OCA\Mail\Migration;
+
+use Closure;
+use OCP\DB\ISchemaWrapper;
+use OCP\Migration\IOutput;
+use OCP\Migration\SimpleMigrationStep;
+
+class Version1090Date20210127160127 extends SimpleMigrationStep {
+	/**
+	 * @param IOutput $output
+	 * @param Closure $schemaClosure The `\Closure` returns a `ISchemaWrapper`
+	 * @param array $options
+	 * @return null|ISchemaWrapper
+	 */
+	public function changeSchema(IOutput $output, Closure $schemaClosure, array $options): ?ISchemaWrapper {
+		/** @var ISchemaWrapper $schema */
+		$schema = $schemaClosure();
+
+		$table = $schema->getTable('mail_accounts');
+		$table->addColumn('sieve_enabled', 'boolean', [
+			'notnull' => true,
+			'default' => false,
+		]);
+		$table->addColumn('sieve_host', 'string', [
+			'notnull' => false,
+			'length' => 64,
+			'default' => null,
+		]);
+		$table->addColumn('sieve_port', 'string', [
+			'notnull' => false,
+			'length' => 6,
+			'default' => null,
+		]);
+		$table->addColumn('sieve_ssl_mode', 'string', [
+			'notnull' => false,
+			'length' => 10,
+			'default' => null,
+		]);
+		$table->addColumn('sieve_user', 'string', [
+			'notnull' => false,
+			'length' => 64,
+			'default' => null,
+		]);
+		$table->addColumn('sieve_password', 'string', [
+			'notnull' => false,
+			'length' => 2048,
+			'default' => null,
+		]);
+
+		return $schema;
+	}
+}
diff --git a/lib/Migration/Version1090Date20210216154409.php b/lib/Migration/Version1090Date20210216154409.php
new file mode 100644
index 000000000..4a793a142
--- /dev/null
+++ b/lib/Migration/Version1090Date20210216154409.php
@@ -0,0 +1,34 @@
+<?php
+
+declare(strict_types=1);
+
+namespace OCA\Mail\Migration;
+
+use Closure;
+use OCP\DB\ISchemaWrapper;
+use OCP\Migration\IOutput;
+use OCP\Migration\SimpleMigrationStep;
+
+class Version1090Date20210216154409 extends SimpleMigrationStep {
+
+
+	/**
+	 * @param IOutput $output
+	 * @param Closure $schemaClosure The `\Closure` returns a `ISchemaWrapper`
+	 * @param array $options
+	 * @return null|ISchemaWrapper
+	 */
+	public function changeSchema(IOutput $output, Closure $schemaClosure, array $options): ?ISchemaWrapper {
+		/** @var ISchemaWrapper $schema */
+		$schema = $schemaClosure();
+
+		$table = $schema->getTable('mail_trusted_senders');
+		$table->addColumn('type', 'string', [
+			'notnull' => true,
+			'default' => 'individual',
+		]);
+		$table->addIndex(['type'], 'mail_trusted_senders_type');
+
+		return $schema;
+	}
+}
diff --git a/lib/Model/IMAPMessage.php b/lib/Model/IMAPMessage.php
index 1841d1cb2..bd8437e72 100644
--- a/lib/Model/IMAPMessage.php
+++ b/lib/Model/IMAPMessage.php
@@ -129,6 +129,7 @@ class IMAPMessage implements IMessage, JsonSerializable {
 	}
 
 	/**
+	 * @deprecated  Seems unused
 	 * @return array
 	 */
 	public function getFlags(): array {
@@ -142,10 +143,12 @@ class IMAPMessage implements IMessage, JsonSerializable {
 			'forwarded' => in_array(Horde_Imap_Client::FLAG_FORWARDED, $flags),
 			'hasAttachments' => $this->hasAttachments($this->fetch->getStructure()),
 			'mdnsent' => in_array(Horde_Imap_Client::FLAG_MDNSENT, $flags, true),
+			'important' => in_array('$important', $flags, true)
 		];
 	}
 
 	/**
+	 * @deprecated  Seems unused
 	 * @param string[] $flags
 	 *
 	 * @throws Exception
@@ -166,7 +169,7 @@ class IMAPMessage implements IMessage, JsonSerializable {
 
 	private function getRawReferences(): string {
 		/** @var Horde_Mime_Headers $headers */
-		$headers = $this->fetch->getHeaders('references', Horde_Imap_Client_Data_Fetch::HEADER_PARSE);
+		$headers = $this->fetch->getHeaderText('0', Horde_Imap_Client_Data_Fetch::HEADER_PARSE);
 		$header = $headers->getHeader('references');
 		if ($header === null) {
 			return '';
@@ -180,7 +183,7 @@ class IMAPMessage implements IMessage, JsonSerializable {
 
 	public function getDispositionNotificationTo(): string {
 		/** @var Horde_Mime_Headers $headers */
-		$headers = $this->fetch->getHeaders('mdn', Horde_Imap_Client_Data_Fetch::HEADER_PARSE);
+		$headers = $this->fetch->getHeaderText('0', Horde_Imap_Client_Data_Fetch::HEADER_PARSE);
 		$header = $headers->getHeader('disposition-notification-to');
 		if ($header === null) {
 			return '';
@@ -345,11 +348,10 @@ class IMAPMessage implements IMessage, JsonSerializable {
 		$fetch_query->flags();
 		$fetch_query->size();
 		$fetch_query->imapDate();
-		$fetch_query->headers(
-			'mdn',
-			['disposition-notification-to'],
-			['cache' => true, 'peek' => true]
-		);
+		$fetch_query->headerText([
+			'cache' => true,
+			'peek' => true,
+		]);
 
 		// $list is an array of Horde_Imap_Client_Data_Fetch objects.
 		$ids = new Horde_Imap_Client_Ids($this->messageId);
@@ -692,7 +694,7 @@ class IMAPMessage implements IMessage, JsonSerializable {
 			in_array('junk', $flags, true)
 		);
 		$msg->setFlagNotjunk(in_array(Horde_Imap_Client::FLAG_NOTJUNK, $flags, true));
-		$msg->setFlagImportant(false);
+		$msg->setFlagImportant(in_array('$important', $flags, true));
 		$msg->setFlagAttachments(false);
 		$msg->setFlagMdnsent(in_array(Horde_Imap_Client::FLAG_MDNSENT, $flags, true));
 
diff --git a/lib/Service/AccountService.php b/lib/Service/AccountService.php
index 90766e98c..13462ff2d 100644
--- a/lib/Service/AccountService.php
+++ b/lib/Service/AccountService.php
@@ -126,6 +126,21 @@ class AccountService {
 	}
 
 	/**
+	 * @param int $accountId
+	 *
+	 * @throws ClientException
+	 */
+	public function deleteByAccountId(int $accountId): void {
+		try {
+			$mailAccount = $this->mapper->findById($accountId);
+		} catch (DoesNotExistException $e) {
+			throw new ClientException("Account $accountId does not exist", 0, $e);
+		}
+		$this->aliasesService->deleteAll($accountId);
+		$this->mapper->delete($mailAccount);
+	}
+
+	/**
 	 * @param MailAccount $newAccount
 	 * @return MailAccount
 	 */
diff --git a/lib/Service/MailManager.php b/lib/Service/MailManager.php
index 444a1aac5..d37278477 100644
--- a/lib/Service/MailManager.php
+++ b/lib/Service/MailManager.php
@@ -26,6 +26,7 @@ namespace OCA\Mail\Service;
 use Horde_Imap_Client;
 use Horde_Imap_Client_Exception;
 use Horde_Imap_Client_Exception_NoSupportExtension;
+use Horde_Imap_Client_Socket;
 use OCA\Mail\Account;
 use OCA\Mail\Contracts\IMailManager;
 use OCA\Mail\Db\Mailbox;
@@ -386,10 +387,13 @@ class MailManager implements IMailManager {
 		}
 
 		// Only send system flags to the IMAP server as other flags might not be supported
-		$imapFlags = self::ALLOWED_FLAGS[$flag] ?? [];
+		$imapFlags = $this->filterFlags($account, $flag, $mailbox);
 		try {
 			foreach ($imapFlags as $imapFlag) {
-				if ($value) {
+				if (empty($imapFlag) === true) {
+					continue;
+				}
+				if ($value === true) {
 					$this->imapMessageMapper->addFlag($client, $mb, $uid, $imapFlag);
 				} else {
 					$this->imapMessageMapper->removeFlag($client, $mb, $uid, $imapFlag);
@@ -502,4 +506,57 @@ class MailManager implements IMailManager {
 		$this->folderMapper->delete($client, $mailbox->getName());
 		$this->mailboxMapper->delete($mailbox);
 	}
+
+	/**
+	 * @param Account $account
+	 * @param Mailbox $mailbox
+	 * @param Message $message
+	 * @return array[]
+	 */
+	public function getMailAttachments(Account $account, Mailbox $mailbox, Message $message): array {
+		return $this->imapMessageMapper->getAttachments($this->imapClientFactory->getClient($account), $mailbox->getName(), $message->getUid());
+	}
+
+	/**
+	 * Filter out IMAP flags that aren't supported by the client server
+	 *
+	 * @param Horde_Imap_Client_Socket $client
+	 * @param string $flag
+	 * @param string $mailbox
+	 * @return array
+	 */
+	public function filterFlags(Account $account, string $flag, string $mailbox): array {
+		// check for RFC server flags
+		if (array_key_exists($flag, self::ALLOWED_FLAGS) === true) {
+			return self::ALLOWED_FLAGS[$flag];
+		}
+
+		// Only allow flag setting if IMAP supports Permaflags
+		// @TODO check if there are length & char limits on permflags
+		if ($this->isPermflagsEnabled($account, $mailbox) === true) {
+			return ["$" . $flag];
+		}
+		return [];
+	}
+
+	/**
+	 * Check IMAP server for support for PERMANENTFLAGS
+	 *
+	 * @param Account $account
+	 * @param string $mailbox
+	 * @return boolean
+	 */
+	public function isPermflagsEnabled(Account $account, string $mailbox): bool {
+		$client = $this->imapClientFactory->getClient($account);
+		try {
+			$capabilities = $client->status($mailbox, Horde_Imap_Client::STATUS_PERMFLAGS);
+		} catch (Horde_Imap_Client_Exception $e) {
+			throw new ServiceException(
+				"Could not get message flag options from IMAP: " . $e->getMessage(),
+				(int) $e->getCode(),
+				$e
+			);
+		}
+		return (is_array($capabilities) === true && array_key_exists('permflags', $capabilities) === true && in_array("\*", $capabilities['permflags'], true) === true);
+	}
 }
diff --git a/lib/Service/MailTransmission.php b/lib/Service/MailTransmission.php
index 4630efff6..729da0374 100644
--- a/lib/Service/MailTransmission.php
+++ b/lib/Service/MailTransmission.php
@@ -26,6 +26,7 @@ namespace OCA\Mail\Service;
 use Horde_Exception;
 use Horde_Imap_Client;
 use Horde_Imap_Client_Data_Fetch;
+use Horde_Imap_Client_DateTime;
 use Horde_Imap_Client_Fetch_Query;
 use Horde_Imap_Client_Ids;
 use Horde_Mail_Transport_Null;
@@ -432,12 +433,12 @@ class MailTransmission implements IMailTransmission {
 		$query->flags();
 		$query->uid();
 		$query->imapDate();
-		$query->headers(
-			'mdn',
-			['disposition-notification-to', 'original-recipient'],
-			['cache' => true, 'peek' => true]
-		);
+		$query->headerText([
+			'cache' => true,
+			'peek' => true,
+		]);
 
+		/** @var Horde_Imap_Client_Data_Fetch[] $fetchResults */
 		$fetchResults = iterator_to_array($imapClient->fetch($mailbox->getName(), $query, [
 			'ids' => new Horde_Imap_Client_Ids([$message->getUid()]),
 		]), false);
@@ -446,10 +447,10 @@ class MailTransmission implements IMailTransmission {
 			throw new ServiceException('Message "' .$message->getId() . '" not found.');
 		}
 
-		/** @var \Horde_Imap_Client_DateTime $imapDate */
+		/** @var Horde_Imap_Client_DateTime $imapDate */
 		$imapDate = $fetchResults[0]->getImapDate();
 		/** @var Horde_Mime_Headers $headers */
-		$mdnHeaders = $fetchResults[0]->getHeaders('mdn', Horde_Imap_Client_Data_Fetch::HEADER_PARSE);
+		$mdnHeaders = $fetchResults[0]->getHeaderText('0', Horde_Imap_Client_Data_Fetch::HEADER_PARSE);
 		/** @var Horde_Mime_Headers_Addresses|null $dispositionNotificationTo */
 		$dispositionNotificationTo = $mdnHeaders->getHeader('disposition-notification-to');
 		/** @var Horde_Mime_Headers_Addresses|null $originalRecipient */
@@ -482,7 +483,10 @@ class MailTransmission implements IMailTransmission {
 				'displayed',
 				$account->getMailAccount()->getOutboundHost(),
 				$smtpClient,
-				['from_addr' => $account->getEMailAddress()]
+				[
+					'from_addr' => $account->getEMailAddress(),
+					'charset' => 'UTF-8',
+				]
 			);
 		} catch (Horde_Mime_Exception $e) {
 			throw new ServiceException('Unable to send mdn for message "' . $message->getId() . '" caused by: ' . $e->getMessage(), 0, $e);
diff --git a/lib/Service/Provisioning/Config.php b/lib/Service/Provisioning/Config.php
index 2af2f1827..74b8cda8d 100644
--- a/lib/Service/Provisioning/Config.php
+++ b/lib/Service/Provisioning/Config.php
@@ -111,6 +111,45 @@ class Config implements JsonSerializable {
 	}
 
 	/**
+	 * @return boolean
+	 */
+	public function getSieveEnabled(): bool {
+		return (bool)$this->data['sieveEnabled'];
+	}
+
+	/**
+	 * @return string
+	 */
+	public function getSieveHost() {
+		return $this->data['sieveHost'];
+	}
+
+	/**
+	 * @return int
+	 */
+	public function getSievePort(): int {
+		return (int)$this->data['sievePort'];
+	}
+
+	/**
+	 * @param IUser $user
+	 * @return string
+	 */
+	public function buildSieveUser(IUser $user) {
+		if (isset($this->data['sieveUser'])) {
+			return $this->buildUserEmail($this->data['sieveUser'], $user);
+		}
+		return $this->buildEmail($user);
+	}
+
+	/**
+	 * @return string
+	 */
+	public function getSieveSslMode() {
+		return $this->data['sieveSslMode'];
+	}
+
+	/**
 	 * Replace %USERID% and %EMAIL% to allow special configurations
 	 *
 	 * @param string $original
diff --git a/lib/Service/Provisioning/Manager.php b/lib/Service/Provisioning/Manager.php
index 906de385f..742c87f13 100644
--- a/lib/Service/Provisioning/Manager.php
+++ b/lib/Service/Provisioning/Manager.php
@@ -100,7 +100,12 @@ class Manager {
 									string $smtpUser,
 									string $smtpHost,
 									int $smtpPort,
-									string $smtpSslMode): void {
+									string $smtpSslMode,
+									bool $sieveEnabled,
+									string $sieveUser,
+									string $sieveHost,
+									int $sievePort,
+									string $sieveSslMode): void {
 		$config = $this->configMapper->save(new Config([
 			'active' => true,
 			'email' => $email,
@@ -112,6 +117,11 @@ class Manager {
 			'smtpHost' => $smtpHost,
 			'smtpPort' => $smtpPort,
 			'smtpSslMode' => $smtpSslMode,
+			'sieveEnabled' => $sieveEnabled,
+			'sieveUser' => $sieveUser,
+			'sieveHost' => $sieveHost,
+			'sievePort' => $sievePort,
+			'sieveSslMode' => $sieveSslMode,
 		]));
 
 		$this->provision($config);
@@ -119,10 +129,7 @@ class Manager {
 
 	private function updateAccount(IUser $user, MailAccount $account, Config $config): MailAccount {
 		$account->setEmail($config->buildEmail($user));
-		if ($user->getDisplayName() !== $user->getUID()) {
-			// Only set if it's something meaningful
-			$account->setName($user->getDisplayName());
-		}
+		$account->setName($user->getDisplayName());
 		$account->setInboundUser($config->buildImapUser($user));
 		$account->setInboundHost($config->getImapHost());
 		$account->setInboundPort($config->getImapPort());
@@ -131,6 +138,19 @@ class Manager {
 		$account->setOutboundHost($config->getSmtpHost());
 		$account->setOutboundPort($config->getSmtpPort());
 		$account->setOutboundSslMode($config->getSmtpSslMode());
+		$account->setSieveEnabled($config->getSieveEnabled());
+
+		if ($config->getSieveEnabled()) {
+			$account->setSieveUser($config->buildSieveUser($user));
+			$account->setSieveHost($config->getSieveHost());
+			$account->setSievePort($config->getSievePort());
+			$account->setSieveSslMode($config->getSieveSslMode());
+		} else {
+			$account->setSieveUser(null);
+			$account->setSieveHost(null);
+			$account->setSievePort(null);
+			$account->setSieveSslMode(null);
+		}
 
 		return $account;
 	}
diff --git a/lib/Service/SetupService.php b/lib/Service/SetupService.php
index 0be5984bf..ffd6146ac 100644
--- a/lib/Service/SetupService.php
+++ b/lib/Service/SetupService.php
@@ -26,9 +26,14 @@ declare(strict_types=1);
 
 namespace OCA\Mail\Service;
 
+use Horde_Imap_Client_Exception;
+use Horde_Mail_Exception;
+use Horde_Mail_Transport_Smtphorde;
 use OCA\Mail\Account;
 use OCA\Mail\Db\MailAccount;
+use OCA\Mail\Exception\CouldNotConnectException;
 use OCA\Mail\Exception\ServiceException;
+use OCA\Mail\IMAP\IMAPClientFactory;
 use OCA\Mail\Service\AutoConfig\AutoConfig;
 use OCA\Mail\SMTP\SmtpClientFactory;
 use OCP\Security\ICrypto;
@@ -48,6 +53,9 @@ class SetupService {
 	/** @var SmtpClientFactory */
 	private $smtpClientFactory;
 
+	/** @var IMAPClientFactory */
+	private $imapClientFactory;
+
 	/** var LoggerInterface */
 	private $logger;
 
@@ -55,11 +63,13 @@ class SetupService {
 								AccountService $accountService,
 								ICrypto $crypto,
 								SmtpClientFactory $smtpClientFactory,
+								IMAPClientFactory $imapClientFactory,
 								LoggerInterface $logger) {
 		$this->autoConfig = $autoConfig;
 		$this->accountService = $accountService;
 		$this->crypto = $crypto;
 		$this->smtpClientFactory = $smtpClientFactory;
+		$this->imapClientFactory = $imapClientFactory;
 		$this->logger = $logger;
 	}
 
@@ -124,12 +134,35 @@ class SetupService {
 
 		$account = new Account($newAccount);
 		$this->logger->debug('Connecting to account {account}', ['account' => $newAccount->getEmail()]);
-		$transport = $this->smtpClientFactory->create($account);
-		$account->testConnectivity($transport);
+		$this->testConnectivity($account);
 
 		$this->accountService->save($newAccount);
 		$this->logger->debug("account created " . $newAccount->getId());
 
 		return $account;
 	}
+
+	/**
+	 * @param Account $account
+	 * @throws CouldNotConnectException
+	 */
+	protected function testConnectivity(Account $account): void {
+		$mailAccount = $account->getMailAccount();
+
+		$imapClient = $this->imapClientFactory->getClient($account);
+		try {
+			$imapClient->login();
+		} catch (Horde_Imap_Client_Exception $e) {
+			throw CouldNotConnectException::create($e, 'IMAP', $mailAccount->getInboundHost(), $mailAccount->getInboundPort());
+		}
+
+		$transport = $this->smtpClientFactory->create($account);
+		if ($transport instanceof Horde_Mail_Transport_Smtphorde) {
+			try {
+				$transport->getSMTPObject();
+			} catch (Horde_Mail_Exception $e) {
+				throw CouldNotConnectException::create($e, 'SMTP', $mailAccount->getOutboundHost(), $mailAccount->getOutboundPort());
+			}
+		}
+	}
 }
diff --git a/lib/Service/TrustedSenderService.php b/lib/Service/TrustedSenderService.php
index 8210be686..57cebbfa6 100644
--- a/lib/Service/TrustedSenderService.php
+++ b/lib/Service/TrustedSenderService.php
@@ -44,7 +44,7 @@ class TrustedSenderService implements ITrustedSenderService {
 		);
 	}
 
-	public function trust(string $uid, string $email, ?bool $trust = true): void {
+	public function trust(string $uid, string $email, string $type, ?bool $trust = true): void {
 		if ($trust && $this->isTrusted($uid, $email)) {
 			// Nothing to do
 			return;
@@ -53,12 +53,14 @@ class TrustedSenderService implements ITrustedSenderService {
 		if ($trust) {
 			$this->mapper->create(
 				$uid,
-				$email
+				$email,
+				$type
 			);
 		} else {
 			$this->mapper->remove(
 				$uid,
-				$email
+				$email,
+				$type
 			);
 		}
 	}
diff --git a/lib/Settings/AdminSettings.php b/lib/Settings/AdminSettings.php
index 532749c85..7e4c47c98 100644
--- a/lib/Settings/AdminSettings.php
+++ b/lib/Settings/AdminSettings.php
@@ -61,6 +61,11 @@ class AdminSettings implements ISettings {
 				'smtpHost' => 'smtp.domain.com',
 				'smtpPort' => 587,
 				'smtpSslMode' => 'tls',
+				'sieveEnabled' => false,
+				'sieveUser' => '%USERID%@domain.com',
+				'sieveHost' => 'imap.domain.com',
+				'sievePort' => 4190,
+				'sieveSslMode' => 'tls',
 			])
 		);
 
diff --git a/lib/Sieve/SieveClientFactory.php b/lib/Sieve/SieveClientFactory.php
new file mode 100644
index 000000000..4e7359741
--- /dev/null
+++ b/lib/Sieve/SieveClientFactory.php
@@ -0,0 +1,116 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * @author Daniel Kesselberg <mail@danielkesselberg.de>
+ *
+ * Mail
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+namespace OCA\Mail\Sieve;
+
+use Horde\ManageSieve;
+use OCA\Mail\Account;
+use OCP\IConfig;
+use OCP\Security\ICrypto;
+
+class SieveClientFactory {
+
+	/** @var ICrypto */
+	private $crypto;
+
+	/** @var IConfig */
+	private $config;
+
+	private $cache = [];
+
+	/**
+	 * @param ICrypto $crypto
+	 * @param IConfig $config
+	 */
+	public function __construct(ICrypto $crypto, IConfig $config) {
+		$this->crypto = $crypto;
+		$this->config = $config;
+	}
+
+	/**
+	 * @param Account $account
+	 * @return ManageSieve
+	 * @throws ManageSieve\Exception
+	 */
+	public function getClient(Account $account): ManageSieve {
+		if (!isset($this->cache[$account->getId()])) {
+			$user = $account->getMailAccount()->getSieveUser();
+			if (empty($user)) {
+				$user = $account->getMailAccount()->getInboundUser();
+			}
+			$password = $account->getMailAccount()->getSievePassword();
+			if (empty($password)) {
+				$password = $account->getMailAccount()->getInboundPassword();
+			}
+
+			$this->cache[$account->getId()] = $this->createClient(
+				$account->getMailAccount()->getSieveHost(),
+				$account->getMailAccount()->getSievePort(),
+				$user,
+				$password,
+				$account->getMailAccount()->getSieveSslMode()
+			);
+		}
+
+		return $this->cache[$account->getId()];
+	}
+
+	/**
+	 * @param string $host
+	 * @param int $port
+	 * @param string $user
+	 * @param string $password
+	 * @param string $sslMode
+	 * @return ManageSieve
+	 * @throws ManageSieve\Exception
+	 */
+	public function createClient(string $host, int $port, string $user, string $password, string $sslMode): ManageSieve {
+		if (empty($sslMode)) {
+			$sslMode = true;
+		} elseif ($sslMode === 'none') {
+			$sslMode = false;
+		}
+
+		$params = [
+			'host' => $host,
+			'port' => $port,
+			'user' => $user,
+			'password' => $this->crypto->decrypt($password),
+			'secure' => $sslMode,
+			'timeout' => (int)$this->config->getSystemValue('app.mail.sieve.timeout', 5),
+			'context' => [
+				'ssl' => [
+					'verify_peer' => $this->config->getSystemValueBool('app.mail.verify-tls-peer', true),
+					'verify_peer_name' => $this->config->getSystemValueBool('app.mail.verify-tls-peer', true),
+
+				]
+			],
+		];
+
+		if ($this->config->getSystemValue('debug', false)) {
+			$params['logger'] = new SieveLogger($this->config->getSystemValue('datadirectory') . '/horde_sieve.log');
+		}
+
+		return new ManageSieve($params);
+	}
+}
diff --git a/lib/Sieve/SieveLogger.php b/lib/Sieve/SieveLogger.php
new file mode 100644
index 000000000..752467cdf
--- /dev/null
+++ b/lib/Sieve/SieveLogger.php
@@ -0,0 +1,46 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * @author Daniel Kesselberg <mail@danielkesselberg.de>
+ *
+ * Mail
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+namespace OCA\Mail\Sieve;
+
+class SieveLogger {
+	/** @var resource */
+	protected $stream;
+
+	public function __construct(string $logFile) {
+		$stream = @fopen($logFile, 'ab');
+		if ($stream === false) {
+			throw new \InvalidArgumentException('Unable to use "' . $logFile . '" as log file for sieve.');
+		}
+		$this->stream = $stream;
+	}
+
+	public function debug(string $message): void {
+		fwrite($this->stream, $message);
+	}
+
+	public function __destruct() {
+		fflush($this->stream);
+		fclose($this->stream);
+	}
+}