Detect missing mailbox cache and block access to messages

Signed-off-by: Christoph Wurst <christoph@winzerhof-wurst.at>

17 files changed, 244 insertions, 103 deletions

diff --git a/lib/Contracts/IMailSearch.php b/lib/Contracts/IMailSearch.php
index 43299907c..ac2a82d3b 100644
--- a/lib/Contracts/IMailSearch.php
+++ b/lib/Contracts/IMailSearch.php
@@ -24,6 +24,7 @@
 namespace OCA\Mail\Contracts;
 
 use OCA\Mail\Account;
+use OCA\Mail\Exception\ClientException;
 use OCA\Mail\Exception\ServiceException;
 use OCA\Mail\Model\IMAPMessage;
 
@@ -36,6 +37,7 @@ interface IMailSearch {
 	 * @param string|null $cursor
 	 *
 	 * @return IMAPMessage[]
+	 * @throws ClientException
 	 * @throws ServiceException
 	 */
 	public function findMessages(Account $account, string $mailboxName, ?string $filter, ?int $cursor): array;
diff --git a/lib/Controller/FoldersController.php b/lib/Controller/FoldersController.php
index 3caa7c051..96442b68f 100644
--- a/lib/Controller/FoldersController.php
+++ b/lib/Controller/FoldersController.php
@@ -26,6 +26,7 @@ declare(strict_types=1);
 namespace OCA\Mail\Controller;
 
 use Horde_Imap_Client;
+use OCA\Mail\Exception\ClientException;
 use OCA\Mail\Exception\MailboxNotCachedException;
 use OCA\Mail\Exception\ServiceException;
 use OCA\Mail\Service\SyncService;
@@ -102,10 +103,12 @@ class FoldersController extends Controller {
 	 * @param string $folderId
 	 * @param string $syncToken
 	 * @param int[] $uids
+	 *
 	 * @return JSONResponse
+	 * @throws ClientException
 	 * @throws ServiceException
 	 */
-	public function sync(int $accountId, string $folderId, array $uids = []): JSONResponse {
+	public function sync(int $accountId, string $folderId, array $uids = [], bool $init = false): JSONResponse {
 		$account = $this->accountService->find($this->currentUserId, $accountId);
 
 		if (empty($accountId) || empty($folderId) || !is_array($uids)) {
@@ -120,7 +123,7 @@ class FoldersController extends Controller {
 				array_map(function($uid) {
 					return (int) $uid;
 				}, $uids),
-				true
+				!$init
 			);
 		} catch (MailboxNotCachedException $e) {
 			return new JSONResponse(null, Http::STATUS_PRECONDITION_REQUIRED);
diff --git a/lib/Controller/MessagesController.php b/lib/Controller/MessagesController.php
index 7e075621e..9a6fc82de 100755
--- a/lib/Controller/MessagesController.php
+++ b/lib/Controller/MessagesController.php
@@ -33,6 +33,7 @@ namespace OCA\Mail\Controller;
 use Exception;
 use OCA\Mail\Contracts\IMailManager;
 use OCA\Mail\Contracts\IMailSearch;
+use OCA\Mail\Exception\ClientException;
 use OCA\Mail\Exception\ServiceException;
 use OCA\Mail\Http\AttachmentDownloadResponse;
 use OCA\Mail\Http\HtmlResponse;
@@ -40,7 +41,6 @@ use OCA\Mail\Model\IMAPMessage;
 use OCA\Mail\Service\AccountService;
 use OCA\Mail\Service\IMailBox;
 use OCA\Mail\Service\ItineraryService;
-use OCA\Mail\Service\SyncService;
 use OCP\AppFramework\Controller;
 use OCP\AppFramework\Db\DoesNotExistException;
 use OCP\AppFramework\Http;
@@ -70,9 +70,6 @@ class MessagesController extends Controller {
 	/** @var ItineraryService */
 	private $itineraryService;
 
-	/** @var SyncService */
-	private $syncService;
-
 	/** @var string */
 	private $currentUserId;
 
@@ -108,7 +105,6 @@ class MessagesController extends Controller {
 								IMailManager $mailManager,
 								IMailSearch $mailSearch,
 								ItineraryService $itineraryService,
-								SyncService $syncService,
 								string $UserId,
 								$userFolder,
 								ILogger $logger,
@@ -121,7 +117,6 @@ class MessagesController extends Controller {
 		$this->mailManager = $mailManager;
 		$this->mailSearch = $mailSearch;
 		$this->itineraryService = $itineraryService;
-		$this->syncService = $syncService;
 		$this->currentUserId = $UserId;
 		$this->userFolder = $userFolder;
 		$this->logger = $logger;
@@ -141,6 +136,7 @@ class MessagesController extends Controller {
 	 * @param string $filter
 	 *
 	 * @return JSONResponse
+	 * @throws ClientException
 	 * @throws ServiceException
 	 */
 	public function index(int $accountId, string $folderId, int $cursor = null, string $filter = null): JSONResponse {
@@ -150,11 +146,6 @@ class MessagesController extends Controller {
 			return new JSONResponse(null, Http::STATUS_FORBIDDEN);
 		}
 
-		$this->syncService->ensurePopulated(
-			$account,
-			base64_decode($folderId)
-		);
-
 		$this->logger->debug("loading messages of folder <$folderId>");
 
 		return new JSONResponse(
diff --git a/lib/Db/Mailbox.php b/lib/Db/Mailbox.php
index c09b3981a..772ad641e 100644
--- a/lib/Db/Mailbox.php
+++ b/lib/Db/Mailbox.php
@@ -127,4 +127,16 @@ class Mailbox extends Entity {
 		return $this->getName();
 	}
 
+	public function isCached(): bool {
+		return $this->getSyncNewToken() !== null
+			&& $this->getSyncChangedToken() !== null
+			&& $this->getSyncVanishedToken() !== null;
+	}
+
+	public function hasLocks(): bool {
+		return $this->getSyncNewLock() !== null
+			|| $this->getSyncChangedLock() !== null
+			|| $this->getSyncVanishedLock() !== null;
+	}
+
 }
diff --git a/lib/Db/MailboxMapper.php b/lib/Db/MailboxMapper.php
index 3acbde53b..6fcb527c5 100644
--- a/lib/Db/MailboxMapper.php
+++ b/lib/Db/MailboxMapper.php
@@ -24,7 +24,7 @@
 namespace OCA\Mail\Db;
 
 use OCA\Mail\Account;
-use OCA\Mail\Exception\ConcurrentSyncException;
+use OCA\Mail\Exception\MailboxLockedException;
 use OCA\Mail\Exception\ServiceException;
 use OCP\AppFramework\Db\DoesNotExistException;
 use OCP\AppFramework\Db\MultipleObjectsReturnedException;
@@ -109,7 +109,7 @@ class MailboxMapper extends QBMapper {
 	}
 
 	/**
-	 * @throws ConcurrentSyncException
+	 * @throws MailboxLockedException
 	 */
 	private function lockForSync(Mailbox $mailbox, string $attr, ?int $lock): int {
 		$now = $this->timeFactory->getTime();
@@ -117,7 +117,7 @@ class MailboxMapper extends QBMapper {
 		if ($lock !== null
 			&& $lock > ($now - 5 * 60)) {
 			// Another process is syncing
-			throw new ConcurrentSyncException($mailbox->getId() . ' is already being synced');
+			throw MailboxLockedException::from($mailbox);
 		}
 
 		$query = $this->db->getQueryBuilder();
@@ -130,14 +130,14 @@ class MailboxMapper extends QBMapper {
 		if ($query->execute() === 0) {
 			// Another process just started syncing
 
-			throw new ConcurrentSyncException();
+			throw MailboxLockedException::from($mailbox);
 		}
 
 		return $now;
 	}
 
 	/**
-	 * @throws ConcurrentSyncException
+	 * @throws MailboxLockedException
 	 */
 	public function lockForNewSync(Mailbox $mailbox): void {
 		$mailbox->setSyncNewLock(
@@ -146,7 +146,7 @@ class MailboxMapper extends QBMapper {
 	}
 
 	/**
-	 * @throws ConcurrentSyncException
+	 * @throws MailboxLockedException
 	 */
 	public function lockForChangeSync(Mailbox $mailbox): void {
 		$mailbox->setSyncChangedLock(
@@ -155,7 +155,7 @@ class MailboxMapper extends QBMapper {
 	}
 
 	/**
-	 * @throws ConcurrentSyncException
+	 * @throws MailboxLockedException
 	 */
 	public function lockForVanishedSync(Mailbox $mailbox): void {
 		$mailbox->setSyncVanishedLock(
diff --git a/lib/Exception/ClientException.php b/lib/Exception/ClientException.php
index b2f212512..3619ee04d 100644
--- a/lib/Exception/ClientException.php
+++ b/lib/Exception/ClientException.php
@@ -27,7 +27,12 @@ declare(strict_types=1);
 namespace OCA\Mail\Exception;
 
 use Exception;
+use OCP\AppFramework\Http;
 
 class ClientException extends Exception {
 
+	public function getHttpCode(): int {
+		return Http::STATUS_BAD_REQUEST;
+	}
+
 }
diff --git a/lib/Exception/ConcurrentSyncException.php b/lib/Exception/MailboxLockedException.php
index 7cc91136d..8f66e50af 100644
--- a/lib/Exception/ConcurrentSyncException.php
+++ b/lib/Exception/MailboxLockedException.php
@@ -23,8 +23,17 @@
 
 namespace OCA\Mail\Exception;
 
-use Exception;
+use OCA\Mail\Db\Mailbox;
+use OCP\AppFramework\Http;
 
-class ConcurrentSyncException extends Exception {
+class MailboxLockedException extends ClientException {
+
+	public static function from(Mailbox $mailbox): self {
+		return new self($mailbox->getId() . ' is already being synced');
+	}
+
+	public function getHttpCode(): int {
+		return Http::STATUS_CONFLICT;
+	}
 
 }
diff --git a/lib/Exception/MailboxNotCachedException.php b/lib/Exception/MailboxNotCachedException.php
index 37242b1ad..728700c92 100644
--- a/lib/Exception/MailboxNotCachedException.php
+++ b/lib/Exception/MailboxNotCachedException.php
@@ -2,6 +2,12 @@
 
 namespace OCA\Mail\Exception;
 
-class MailboxNotCachedException extends ServiceException {
+use OCA\Mail\Db\Mailbox;
+
+class MailboxNotCachedException extends ClientException {
+
+	public static function from(Mailbox $mailbox): self {
+		return new self("mailbox {$mailbox->getId()} is not cached");
+	}
 
 }
diff --git a/lib/Http/JsonResponse.php b/lib/Http/JsonResponse.php
index c647e5089..8c5cc9396 100644
--- a/lib/Http/JsonResponse.php
+++ b/lib/Http/JsonResponse.php
@@ -25,6 +25,7 @@ declare(strict_types=1);
 
 namespace OCA\Mail\Http;
 
+use OCA\Mail\Exception\ClientException;
 use OCP\AppFramework\Http;
 use OCP\AppFramework\Http\JSONResponse as Base;
 use Throwable;
@@ -40,7 +41,7 @@ use function get_class;
 class JsonResponse extends Base {
 
 	public function __construct($data = [],
-						 int $statusCode = Http::STATUS_OK) {
+								int $statusCode = Http::STATUS_OK) {
 		parent::__construct($data, $statusCode);
 
 		$this->addHeader('x-mail-response', 'true');
@@ -68,6 +69,16 @@ class JsonResponse extends Base {
 		);
 	}
 
+	public static function failWith(ClientException $exception): self {
+		return self::fail(
+			[
+				'message' => $exception->getMessage(),
+				'type' => get_class($exception),
+			],
+			$exception->getHttpCode()
+		);
+	}
+
 	public static function error(string $message,
 								 int $status = Http::STATUS_INTERNAL_SERVER_ERROR,
 								 array $data = [],
diff --git a/lib/Http/Middleware/ErrorMiddleware.php b/lib/Http/Middleware/ErrorMiddleware.php
index 07fd4130e..3890faaa6 100644
--- a/lib/Http/Middleware/ErrorMiddleware.php
+++ b/lib/Http/Middleware/ErrorMiddleware.php
@@ -76,9 +76,7 @@ class ErrorMiddleware extends Middleware {
 		}
 
 		if ($exception instanceof ClientException) {
-			return JsonResponse::fail([
-				'message' => $exception->getMessage()
-			]);
+			return JsonResponse::failWith($exception);
 		}
 
 		if ($exception instanceof DoesNotExistException) {
diff --git a/lib/Service/Search/MailSearch.php b/lib/Service/Search/MailSearch.php
index 1927af9aa..290f1fb1c 100644
--- a/lib/Service/Search/MailSearch.php
+++ b/lib/Service/Search/MailSearch.php
@@ -30,6 +30,9 @@ use OCA\Mail\Db\Mailbox;
 use OCA\Mail\Db\MailboxMapper;
 use OCA\Mail\Db\Message;
 use OCA\Mail\Db\MessageMapper;
+use OCA\Mail\Exception\ClientException;
+use OCA\Mail\Exception\MailboxLockedException;
+use OCA\Mail\Exception\MailboxNotCachedException;
 use OCA\Mail\Exception\ServiceException;
 use OCA\Mail\IMAP\Search\Provider as ImapSearchProvider;
 use OCP\AppFramework\Db\DoesNotExistException;
@@ -71,6 +74,7 @@ class MailSearch implements IMailSearch {
 	 * @param string|null $cursor
 	 *
 	 * @return Message[]
+	 * @throws ClientException
 	 * @throws ServiceException
 	 */
 	public function findMessages(Account $account,
@@ -83,6 +87,13 @@ class MailSearch implements IMailSearch {
 			throw new ServiceException('Mailbox does not exist', 0, $e);
 		}
 
+		if ($mailbox->hasLocks()) {
+			throw MailboxLockedException::from($mailbox);
+		}
+		if (!$mailbox->isCached()) {
+			throw MailboxNotCachedException::from($mailbox);
+		}
+
 		$query = $this->filterStringParser->parse($filter);
 		if ($cursor !== null) {
 			$query->setCursor($cursor);
diff --git a/lib/Service/SyncService.php b/lib/Service/SyncService.php
index 6a084a575..b99caf1c3 100644
--- a/lib/Service/SyncService.php
+++ b/lib/Service/SyncService.php
@@ -32,7 +32,8 @@ use OCA\Mail\Db\MailboxMapper;
 use OCA\Mail\Db\Message;
 use OCA\Mail\Db\MessageMapper;
 use OCA\Mail\Db\MessageMapper as DatabaseMessageMapper;
-use OCA\Mail\Exception\ConcurrentSyncException;
+use OCA\Mail\Exception\ClientException;
+use OCA\Mail\Exception\MailboxLockedException;
 use OCA\Mail\Exception\MailboxNotCachedException;
 use OCA\Mail\Exception\ServiceException;
 use OCA\Mail\IMAP\IMAPClientFactory;
@@ -51,6 +52,57 @@ use function array_map;
 
 class SyncService {
 
+	/**
+	 * @param int[] $knownUids
+	 *
+	 * @throws ClientException
+	 * @throws ServiceException
+	 */
+	private function sync(Account $account,
+						  Mailbox $mailbox,
+						  int $criteria,
+						  array $knownUids = null,
+						  bool $force = false): Response {
+		if ($mailbox->getSelectable() === false) {
+			return new Response();
+		}
+
+		if ($criteria & Horde_Imap_Client::SYNC_NEWMSGSUIDS) {
+			$this->mailboxMapper->lockForNewSync($mailbox);
+		}
+		if ($criteria & Horde_Imap_Client::SYNC_FLAGSUIDS) {
+			$this->mailboxMapper->lockForChangeSync($mailbox);
+		}
+		if ($criteria & Horde_Imap_Client::SYNC_VANISHEDUIDS) {
+			$this->mailboxMapper->lockForVanishedSync($mailbox);
+		}
+
+		try {
+			if ($force
+				|| $mailbox->getSyncNewToken() === null
+				|| $mailbox->getSyncChangedToken() === null
+				|| $mailbox->getSyncVanishedToken() === null) {
+				$response = $this->runInitialSync($account, $mailbox);
+			} else {
+				$response = $this->runPartialSync($account, $mailbox, $criteria, $knownUids);
+			}
+		} catch (Throwable $e) {
+			throw new ServiceException('Sync failed', 0, $e);
+		} finally {
+			if ($criteria & Horde_Imap_Client::SYNC_VANISHEDUIDS) {
+				$this->mailboxMapper->unlockFromVanishedSync($mailbox);
+			}
+			if ($criteria & Horde_Imap_Client::SYNC_FLAGSUIDS) {
+				$this->mailboxMapper->unlockFromChangedSync($mailbox);
+			}
+			if ($criteria & Horde_Imap_Client::SYNC_NEWMSGSUIDS) {
+				$this->mailboxMapper->unlockFromNewSync($mailbox);
+			}
+		}
+
+		return $response;
+	}
+
 	/** @var DatabaseMessageMapper */
 	private $dbMapper;
 
@@ -94,6 +146,7 @@ class SyncService {
 	}
 
 	/**
+	 * @throws ClientException
 	 * @throws ServiceException
 	 */
 	public function syncAccount(Account $account,
@@ -113,6 +166,7 @@ class SyncService {
 	/**
 	 * @param int[] $knownUids
 	 *
+	 * @throws ClientException
 	 * @throws ServiceException
 	 */
 	public function syncMailbox(Account $account,
@@ -123,8 +177,8 @@ class SyncService {
 		try {
 			$mb = $this->mailboxMapper->find($account, $mailbox);
 
-			if ($partialOnly && $mb->getSyncNewToken() === null) {
-				throw new MailboxNotCachedException();
+			if ($partialOnly && !$mb->isCached()) {
+				throw MailboxNotCachedException::from($mb);
 			}
 
 			return $this->sync(
@@ -158,7 +212,7 @@ class SyncService {
 			$this->mailboxMapper->lockForVanishedSync($mb);
 
 			$this->runInitialSync($account, $mb);
-		} catch (ConcurrentSyncException $e) {
+		} catch (MailboxLockedException $e) {
 			// Fine, then we don't have to do it
 		} finally {
 			$this->mailboxMapper->unlockFromNewSync($mb);
@@ -168,60 +222,6 @@ class SyncService {
 	}
 
 	/**
-	 * @param int[] $knownUids
-	 *
-	 * @throws ServiceException
-	 */
-	private function sync(Account $account,
-						  Mailbox $mailbox,
-						  int $criteria,
-						  array $knownUids = null,
-						  bool $force = false): Response {
-		if ($mailbox->getSelectable() === false) {
-			return new Response();
-		}
-
-		try {
-			if ($criteria & Horde_Imap_Client::SYNC_NEWMSGSUIDS) {
-				$this->mailboxMapper->lockForNewSync($mailbox);
-			}
-			if ($criteria & Horde_Imap_Client::SYNC_FLAGSUIDS) {
-				$this->mailboxMapper->lockForChangeSync($mailbox);
-			}
-			if ($criteria & Horde_Imap_Client::SYNC_VANISHEDUIDS) {
-				$this->mailboxMapper->lockForVanishedSync($mailbox);
-			}
-		} catch (ConcurrentSyncException $e) {
-			throw new ServiceException('Another sync is in progress for ' . $mailbox->getId(), 0, $e);
-		}
-
-		try {
-			if ($force
-				|| $mailbox->getSyncNewToken() === null
-				|| $mailbox->getSyncChangedToken() === null
-				|| $mailbox->getSyncVanishedToken() === null) {
-				$response = $this->runInitialSync($account, $mailbox);
-			} else {
-				$response = $this->runPartialSync($account, $mailbox, $criteria, $knownUids);
-			}
-		} catch (Throwable $e) {
-			throw new ServiceException('Sync failed', 0, $e);
-		} finally {
-			if ($criteria & Horde_Imap_Client::SYNC_VANISHEDUIDS) {
-				$this->mailboxMapper->unlockFromVanishedSync($mailbox);
-			}
-			if ($criteria & Horde_Imap_Client::SYNC_FLAGSUIDS) {
-				$this->mailboxMapper->unlockFromChangedSync($mailbox);
-			}
-			if ($criteria & Horde_Imap_Client::SYNC_NEWMSGSUIDS) {
-				$this->mailboxMapper->unlockFromNewSync($mailbox);
-			}
-		}
-
-		return $response;
-	}
-
-	/**
 	 * @throws ServiceException
 	 */
 	private function runInitialSync(Account $account, Mailbox $mailbox): Response {
diff --git a/src/components/FolderContent.vue b/src/components/FolderContent.vue
index 78a5abdb3..23baf2631 100644
--- a/src/components/FolderContent.vue
+++ b/src/components/FolderContent.vue
@@ -2,10 +2,12 @@
 	<AppContent>
 		<AppDetailsToggle v-if="showMessage" @close="hideMessage" />
 		<div id="app-content-wrapper">
+			<Error v-if="error" :error="t('mail', 'Could not open mailbox')" message="" />
+			<Loading v-else-if="loadingEnvelopes" :hint="t('mail', 'Loading messages')" />
 			<Loading
-				v-if="loading"
+				v-else-if="loadingCacheInitialization"
 				:hint="t('mail', 'Loading messages')"
-				:slow-hint="t('mail', 'This can take a bit longer when the mailbox is accessed for the first time.')"
+				:slow-hint="t('mail', 'Indexing your messages. This can take a bit longer for larger mailboxes.')"
 			/>
 			<template v-else>
 				<EnvelopeList
@@ -29,6 +31,7 @@ import isMobile from '@nextcloud/vue/dist/Mixins/isMobile'
 
 import AppDetailsToggle from './AppDetailsToggle'
 import EnvelopeList from './EnvelopeList'
+import Error from './Error'
 import Loading from './Loading'
 import Logger from '../logger'
 import Message from './Message'
@@ -41,6 +44,7 @@ export default {
 		AppContent,
 		AppDetailsToggle,
 		EnvelopeList,
+		Error,
 		Loading,
 		Message,
 		NewMessageDetail,
@@ -59,7 +63,9 @@ export default {
 	},
 	data() {
 		return {
-			loading: true,
+			error: false,
+			loadingEnvelopes: true,
+			loadingCacheInitialization: false,
 			searchQuery: undefined,
 			alive: false,
 		}
@@ -94,7 +100,7 @@ export default {
 		$route(to, from) {
 			if (to.name === 'folder') {
 				// Navigate (back) to the folder view -> (re)fetch data
-				this.fetchData()
+				this.loadEnvelopes()
 			}
 		},
 	},
@@ -103,14 +109,31 @@ export default {
 
 		new OCA.Search(this.searchProxy, this.clearSearchProxy)
 
-		this.fetchData()
+		this.loadEnvelopes()
 	},
 	beforeDestroy() {
 		this.alive = false
 	},
 	methods: {
-		fetchData() {
-			this.loading = true
+		initializeCache() {
+			this.loadingCacheInitialization = true
+			this.error = false
+
+			this.$store
+				.dispatch('syncEnvelopes', {
+					accountId: this.account.id,
+					folderId: this.folder.id,
+					init: true,
+				})
+				.then(() => {
+					this.loadingCacheInitialization = false
+
+					return this.loadEnvelopes()
+				})
+		},
+		loadEnvelopes() {
+			this.loadingEnvelopes = true
+			this.error = false
 
 			this.$store
 				.dispatch('fetchEnvelopes', {
@@ -122,7 +145,7 @@ export default {
 					const envelopes = this.envelopes
 					Logger.debug('envelopes fetched', envelopes)
 
-					this.loading = false
+					this.loadingEnvelopes = false
 
 					if (!this.isMobile && this.$route.name !== 'message' && envelopes.length > 0) {
 						// Show first message
@@ -140,6 +163,14 @@ export default {
 						})
 					}
 				})
+				.catch(error => {
+					if (error.name === 'MailboxNotCachedException') {
+						this.loadingEnvelopes = false
+
+						return this.initializeCache()
+					}
+					this.error = {}
+				})
 		},
 		hideMessage() {
 			this.$router.replace({
@@ -163,7 +194,7 @@ export default {
 		search(query) {
 			this.searchQuery = query
 
-			this.fetchData()
+			this.loadEnvelopes()
 		},
 		clearSearch() {
 			this.searchQuery = undefined
diff --git a/src/service/MessageService.js b/src/service/MessageService.js
index 0b2861a70..9e2fdbfac 100644
--- a/src/service/MessageService.js
+++ b/src/service/MessageService.js
@@ -1,8 +1,17 @@
 import {generateUrl} from '@nextcloud/router'
 import axios from '@nextcloud/axios'
 
+import logger from '../logger'
 import {parseErrorResponse} from '../http/ErrorResponseParser'
 
+export class MailboxNotCachedException extends Error {
+	constructor(message) {
+		super(message)
+		this.name = 'MailboxNotCachedException'
+		this.message = message
+	}
+}
+
 export function fetchEnvelopes(accountId, folderId, query, cursor) {
 	const url = generateUrl('/apps/mail/api/accounts/{accountId}/folders/{folderId}/messages', {
 		accountId,
@@ -22,9 +31,21 @@ export function fetchEnvelopes(accountId, folderId, query, cursor) {
 			params: params,
 		})
 		.then(resp => resp.data)
+		.catch(error => {
+			if (
+				error.response &&
+				error.response.status === 400 &&
+				'x-mail-response' in error.response.headers &&
+				error.response.data.data.type === 'OCA\\Mail\\Exception\\MailboxNotCachedException'
+			) {
+				logger.debug(`mailbox ${folderId} of account ${accountId} is not cached`)
+				throw new MailboxNotCachedException()
+			}
+			throw error
+		})
 }
 
-export function syncEnvelopes(accountId, folderId, uids) {
+export function syncEnvelopes(accountId, folderId, uids, init = false) {
 	const url = generateUrl('/apps/mail/api/accounts/{accountId}/folders/{folderId}/sync', {
 		accountId,
 		folderId,
@@ -34,6 +55,7 @@ export function syncEnvelopes(accountId, folderId, uids) {
 		.get(url, {
 			params: {
 				uids,
+				init,
 			},
 		})
 		.then(resp => resp.data)
diff --git a/src/store/actions.js b/src/store/actions.js
index ca5e4a321..4c09f1343 100644
--- a/src/store/actions.js
+++ b/src/store/actions.js
@@ -334,7 +334,7 @@ export default {
 			return envelopes
 		})
 	},
-	syncEnvelopes({commit, getters, dispatch}, {accountId, folderId}) {
+	syncEnvelopes({commit, getters, dispatch}, {accountId, folderId, init = false}) {
 		const folder = getters.getFolder(accountId, folderId)
 
 		if (folder.isUnified) {
@@ -350,6 +350,7 @@ export default {
 									dispatch('syncEnvelopes', {
 										accountId: account.id,
 										folderId: folder.id,
+										init,
 									})
 								)
 						)
@@ -359,7 +360,7 @@ export default {
 
 		const uids = getters.getEnvelopes(accountId, folderId).map(env => env.id)
 
-		return syncEnvelopes(accountId, folderId, uids).then(syncData => {
+		return syncEnvelopes(accountId, folderId, uids, init).then(syncData => {
 			const unifiedFolder = getters.getUnifiedFolder(folder.specialRole)
 
 			syncData.newMessages.forEach(envelope => {
diff --git a/tests/Unit/Controller/MessagesControllerTest.php b/tests/Unit/Controller/MessagesControllerTest.php
index 0b215c557..1178a03c4 100644
--- a/tests/Unit/Controller/MessagesControllerTest.php
+++ b/tests/Unit/Controller/MessagesControllerTest.php
@@ -38,7 +38,6 @@ use OCA\Mail\Model\Message;
 use OCA\Mail\Service\AccountService;
 use OCA\Mail\Service\ItineraryService;
 use OCA\Mail\Service\MailManager;
-use OCA\Mail\Service\SyncService;
 use OCP\AppFramework\Db\DoesNotExistException;
 use OCP\AppFramework\Http;
 use OCP\AppFramework\Http\ContentSecurityPolicy;
@@ -72,9 +71,6 @@ class MessagesControllerTest extends TestCase {
 	/** @var ItineraryService|MockObject */
 	private $itineraryService;
 
-	/** @var SyncService|MockObject */
-	private $syncService;
-
 	/** @var string */
 	private $userId;
 
@@ -120,7 +116,6 @@ class MessagesControllerTest extends TestCase {
 		$this->mailManager = $this->createMock(IMailManager::class);
 		$this->mailSearch = $this->createMock(IMailSearch::class);
 		$this->itineraryService = $this->createMock(ItineraryService::class);
-		$this->syncService = $this->createMock(SyncService::class);
 		$this->userId = 'john';
 		$this->userFolder = $this->createMock(Folder::class);
 		$this->request = $this->createMock(Request::class);
@@ -145,7 +140,6 @@ class MessagesControllerTest extends TestCase {
 			$this->mailManager,
 			$this->mailSearch,
 			$this->itineraryService,
-			$this->syncService,
 			$this->userId,
 			$this->userFolder,
 			$this->logger,
diff --git a/tests/Unit/Service/MailSearchTest.php b/tests/Unit/Service/MailSearchTest.php
index 2b5006ef4..410ef372d 100644
--- a/tests/Unit/Service/MailSearchTest.php
+++ b/tests/Unit/Service/MailSearchTest.php
@@ -27,8 +27,11 @@ use ChristophWurst\Nextcloud\Testing\TestCase;
 use Horde_Imap_Client_Fetch_Results;
 use Horde_Imap_Client_Socket;
 use OCA\Mail\Account;
+use OCA\Mail\Db\Mailbox;
 use OCA\Mail\Db\MailboxMapper;
 use OCA\Mail\Db\MessageMapper;
+use OCA\Mail\Exception\MailboxLockedException;
+use OCA\Mail\Exception\MailboxNotCachedException;
 use OCA\Mail\IMAP\IMAPClientFactory;
 use OCA\Mail\IMAP\Search\Provider;
 use OCA\Mail\Service\Search\FilterStringParser;
@@ -74,8 +77,50 @@ class MailSearchTest extends TestCase {
 		);
 	}
 
+	public function testFindMessagesNotCached() {
+		$account = $this->createMock(Account::class);
+		$mailbox = new Mailbox();
+		$mailbox->setSyncNewToken('abc');
+		$mailbox->setSyncChangedToken('def');
+		$this->mailboxMapper->expects($this->once())
+			->method('find')
+			->willReturn($mailbox);
+		$this->expectException(MailboxNotCachedException::class);
+
+		$messages = $this->search->findMessages(
+			$account,
+			'INBOX',
+			null,
+			null
+		);
+	}
+
+	public function testFindMessagesLocked() {
+		$account = $this->createMock(Account::class);
+		$mailbox = new Mailbox();
+		$mailbox->setSyncNewLock(123);
+		$this->mailboxMapper->expects($this->once())
+			->method('find')
+			->willReturn($mailbox);
+		$this->expectException(MailboxLockedException::class);
+
+		$messages = $this->search->findMessages(
+			$account,
+			'INBOX',
+			null,
+			null
+		);
+	}
+
 	public function testNoFindMessages() {
 		$account = $this->createMock(Account::class);
+		$mailbox = new Mailbox();
+		$mailbox->setSyncNewToken('abc');
+		$mailbox->setSyncChangedToken('def');
+		$mailbox->setSyncVanishedToken('ghi');
+		$this->mailboxMapper->expects($this->once())
+			->method('find')
+			->willReturn($mailbox);
 
 		$messages = $this->search->findMessages(
 			$account,