Update incoming emails documents

1 files changed, 1 insertions, 353 deletions

diff --git a/doc/administration/reply_by_email.md b/doc/administration/reply_by_email.md
index 3a2cced37bf..426245c7aca 100644
--- a/doc/administration/reply_by_email.md
+++ b/doc/administration/reply_by_email.md
@@ -5,33 +5,7 @@ replying to notification emails.
 
 ## Requirement
 
-Reply by email requires an IMAP-enabled email account. GitLab allows you to use
-three strategies for this feature:
-- using email sub-addressing
-- using a dedicated email address
-- using a catch-all mailbox
-
-### Email sub-addressing
-
-**If your provider or server supports email sub-addressing, we recommend using it.
-Some features (e.g. create new issue via email) only work with sub-addressing.**
-
-[Sub-addressing](https://en.wikipedia.org/wiki/Email_address#Sub-addressing) is
-a feature where any email to `user+some_arbitrary_tag@example.com` will end up
-in the mailbox for `user@example.com`, and is supported by providers such as
-Gmail, Google Apps, Yahoo! Mail, Outlook.com and iCloud, as well as the Postfix
-mail server which you can run on-premises.
-
-### Dedicated email address
-
-This solution is really simple to set up: you just have to create an email
-address dedicated to receive your users' replies to GitLab notifications.
-
-### Catch-all mailbox
-
-A [catch-all mailbox](https://en.wikipedia.org/wiki/Catch-all) for a domain will
-"catch all" the emails addressed to the domain that do not exist in the mail
-server.
+Make sure [incoming email](incoming_email.md) is setup.
 
 ## How it works?
 
@@ -65,329 +39,3 @@ the entity the notification was about (issue, merge request, commit...).
 
 For more details about the `Message-ID`, `In-Reply-To`, and `References headers`,
 please consult [RFC 5322](https://tools.ietf.org/html/rfc5322#section-3.6.4).
-
-## Set it up
-
-If you want to use Gmail / Google Apps with Reply by email, make sure you have
-[IMAP access enabled](https://support.google.com/mail/troubleshooter/1668960?hl=en#ts=1665018)
-and [allowed less secure apps to access the account](https://support.google.com/accounts/answer/6010255)
-or [turn-on 2-step validation](https://support.google.com/accounts/answer/185839)
-and use [an application password](https://support.google.com/mail/answer/185833).
-
-To set up a basic Postfix mail server with IMAP access on Ubuntu, follow the
-[Postfix setup documentation](reply_by_email_postfix_setup.md).
-
-### Security Concerns
-
-**WARNING:** Be careful when choosing the domain used for receiving incoming
-email.
-
-For the sake of example, suppose your top-level company domain is `hooli.com`.
-All employees in your company have an email address at that domain via Google
-Apps, and your company's private Slack instance requires a valid `@hooli.com`
-email address in order to sign up.
-
-If you also host a public-facing GitLab instance at `hooli.com` and set your
-incoming email domain to `hooli.com`, an attacker could abuse the "Create new
-issue by email" or
-"[Create new merge request by email](../user/project/merge_requests/index.md#create-new-merge-requests-by-email)"
-features by using a project's unique address as the email when signing up for
-Slack, which would send a confirmation email, which would create a new issue or
-merge request on the project owned by the attacker, allowing them to click the
-confirmation link and validate their account on your company's private Slack
-instance.
-
-We recommend receiving incoming email on a subdomain, such as
-`incoming.hooli.com`, and ensuring that you do not employ any services that
-authenticate solely based on access to an email domain such as `*.hooli.com.`
-Alternatively, use a dedicated domain for GitLab email communications such as
-`hooli-gitlab.com`.
-
-See GitLab issue [#30366](https://gitlab.com/gitlab-org/gitlab-ce/issues/30366)
-for a real-world example of this exploit.
-
-### Omnibus package installations
-
-1. Find the `incoming_email` section in `/etc/gitlab/gitlab.rb`, enable the
-  feature and fill in the details for your specific IMAP server and email account:
-
-    ```ruby
-    # Configuration for Postfix mail server, assumes mailbox incoming@gitlab.example.com
-    gitlab_rails['incoming_email_enabled'] = true
-
-    # The email address including the `%{key}` placeholder that will be replaced to reference the item being replied to.
-    # The placeholder can be omitted but if present, it must appear in the "user" part of the address (before the `@`).
-    gitlab_rails['incoming_email_address'] = "incoming+%{key}@gitlab.example.com"
-
-    # Email account username
-    # With third party providers, this is usually the full email address.
-    # With self-hosted email servers, this is usually the user part of the email address.
-    gitlab_rails['incoming_email_email'] = "incoming"
-    # Email account password
-    gitlab_rails['incoming_email_password'] = "[REDACTED]"
-
-    # IMAP server host
-    gitlab_rails['incoming_email_host'] = "gitlab.example.com"
-    # IMAP server port
-    gitlab_rails['incoming_email_port'] = 143
-    # Whether the IMAP server uses SSL
-    gitlab_rails['incoming_email_ssl'] = false
-    # Whether the IMAP server uses StartTLS
-    gitlab_rails['incoming_email_start_tls'] = false
-
-    # The mailbox where incoming mail will end up. Usually "inbox".
-    gitlab_rails['incoming_email_mailbox_name'] = "inbox"
-    # The IDLE command timeout.
-    gitlab_rails['incoming_email_idle_timeout'] = 60
-    ```
-
-    ```ruby
-    # Configuration for Gmail / Google Apps, assumes mailbox gitlab-incoming@gmail.com
-    gitlab_rails['incoming_email_enabled'] = true
-
-    # The email address including the `%{key}` placeholder that will be replaced to reference the item being replied to.
-    # The placeholder can be omitted but if present, it must appear in the "user" part of the address (before the `@`).
-    gitlab_rails['incoming_email_address'] = "gitlab-incoming+%{key}@gmail.com"
-
-    # Email account username
-    # With third party providers, this is usually the full email address.
-    # With self-hosted email servers, this is usually the user part of the email address.
-    gitlab_rails['incoming_email_email'] = "gitlab-incoming@gmail.com"
-    # Email account password
-    gitlab_rails['incoming_email_password'] = "[REDACTED]"
-
-    # IMAP server host
-    gitlab_rails['incoming_email_host'] = "imap.gmail.com"
-    # IMAP server port
-    gitlab_rails['incoming_email_port'] = 993
-    # Whether the IMAP server uses SSL
-    gitlab_rails['incoming_email_ssl'] = true
-    # Whether the IMAP server uses StartTLS
-    gitlab_rails['incoming_email_start_tls'] = false
-
-    # The mailbox where incoming mail will end up. Usually "inbox".
-    gitlab_rails['incoming_email_mailbox_name'] = "inbox"
-    # The IDLE command timeout.
-    gitlab_rails['incoming_email_idle_timeout'] = 60
-    ```
-
-    ```ruby
-    # Configuration for Microsoft Exchange mail server w/ IMAP enabled, assumes mailbox incoming@exchange.example.com
-    gitlab_rails['incoming_email_enabled'] = true
-
-    # The email address replies are sent to - Exchange does not support sub-addressing so %{key} is not used here
-    gitlab_rails['incoming_email_address'] = "incoming@exchange.example.com"
-
-    # Email account username
-    # Typically this is the userPrincipalName (UPN)
-    gitlab_rails['incoming_email_email'] = "incoming@ad-domain.example.com"
-    # Email account password
-    gitlab_rails['incoming_email_password'] = "[REDACTED]"
-
-    # IMAP server host
-    gitlab_rails['incoming_email_host'] = "exchange.example.com"
-    # IMAP server port
-    gitlab_rails['incoming_email_port'] = 993
-    # Whether the IMAP server uses SSL
-    gitlab_rails['incoming_email_ssl'] = true
-    ```
-
-1. Reconfigure GitLab for the changes to take effect:
-
-    ```sh
-    sudo gitlab-ctl reconfigure
-    ```
-
-1. Verify that everything is configured correctly:
-
-    ```sh
-    sudo gitlab-rake gitlab:incoming_email:check
-    ```
-
-1. Reply by email should now be working.
-
-### Installations from source
-
-1. Go to the GitLab installation directory:
-
-    ```sh
-    cd /home/git/gitlab
-    ```
-
-1. Find the `incoming_email` section in `config/gitlab.yml`, enable the feature
-  and fill in the details for your specific IMAP server and email account:
-
-    ```sh
-    sudo editor config/gitlab.yml
-    ```
-
-    ```yaml
-    # Configuration for Postfix mail server, assumes mailbox incoming@gitlab.example.com
-    incoming_email:
-      enabled: true
-
-      # The email address including the `%{key}` placeholder that will be replaced to reference the item being replied to.
-      # The placeholder can be omitted but if present, it must appear in the "user" part of the address (before the `@`).
-      address: "incoming+%{key}@gitlab.example.com"
-
-      # Email account username
-      # With third party providers, this is usually the full email address.
-      # With self-hosted email servers, this is usually the user part of the email address.
-      user: "incoming"
-      # Email account password
-      password: "[REDACTED]"
-
-      # IMAP server host
-      host: "gitlab.example.com"
-      # IMAP server port
-      port: 143
-      # Whether the IMAP server uses SSL
-      ssl: false
-      # Whether the IMAP server uses StartTLS
-      start_tls: false
-
-      # The mailbox where incoming mail will end up. Usually "inbox".
-      mailbox: "inbox"
-      # The IDLE command timeout.
-      idle_timeout: 60
-    ```
-
-    ```yaml
-    # Configuration for Gmail / Google Apps, assumes mailbox gitlab-incoming@gmail.com
-    incoming_email:
-      enabled: true
-
-      # The email address including the `%{key}` placeholder that will be replaced to reference the item being replied to.
-      # The placeholder can be omitted but if present, it must appear in the "user" part of the address (before the `@`).
-      address: "gitlab-incoming+%{key}@gmail.com"
-
-      # Email account username
-      # With third party providers, this is usually the full email address.
-      # With self-hosted email servers, this is usually the user part of the email address.
-      user: "gitlab-incoming@gmail.com"
-      # Email account password
-      password: "[REDACTED]"
-
-      # IMAP server host
-      host: "imap.gmail.com"
-      # IMAP server port
-      port: 993
-      # Whether the IMAP server uses SSL
-      ssl: true
-      # Whether the IMAP server uses StartTLS
-      start_tls: false
-
-      # The mailbox where incoming mail will end up. Usually "inbox".
-      mailbox: "inbox"
-      # The IDLE command timeout.
-      idle_timeout: 60
-    ```
-
-    ```yaml
-    # Configuration for Microsoft Exchange mail server w/ IMAP enabled, assumes mailbox incoming@exchange.example.com
-    incoming_email:
-      enabled: true
-
-      # The email address replies are sent to - Exchange does not support sub-addressing so %{key} is not used here
-      address: "incoming@exchange.example.com"
-
-      # Email account username
-      # Typically this is the userPrincipalName (UPN)
-      user: "incoming@ad-domain.example.com"
-      # Email account password
-      password: "[REDACTED]"
-
-      # IMAP server host
-      host: "exchange.example.com"
-      # IMAP server port
-      port: 993
-      # Whether the IMAP server uses SSL
-      ssl: true
-      # Whether the IMAP server uses StartTLS
-      start_tls: false
-
-      # The mailbox where incoming mail will end up. Usually "inbox".
-      mailbox: "inbox"
-      # The IDLE command timeout.
-      idle_timeout: 60
-    ```
-
-1. Enable `mail_room` in the init script at `/etc/default/gitlab`:
-
-    ```sh
-    sudo mkdir -p /etc/default
-    echo 'mail_room_enabled=true' | sudo tee -a /etc/default/gitlab
-    ```
-
-1. Restart GitLab:
-
-    ```sh
-    sudo service gitlab restart
-    ```
-
-1. Verify that everything is configured correctly:
-
-    ```sh
-    sudo -u git -H bundle exec rake gitlab:incoming_email:check RAILS_ENV=production
-    ```
-
-1. Reply by email should now be working.
-
-### Development
-
-1. Go to the GitLab installation directory.
-
-1. Find the `incoming_email` section in `config/gitlab.yml`, enable the feature and fill in the details for your specific IMAP server and email account:
-
-    ```yaml
-    # Configuration for Gmail / Google Apps, assumes mailbox gitlab-incoming@gmail.com
-    incoming_email:
-      enabled: true
-
-      # The email address including the `%{key}` placeholder that will be replaced to reference the item being replied to.
-      # The placeholder can be omitted but if present, it must appear in the "user" part of the address (before the `@`).
-      address: "gitlab-incoming+%{key}@gmail.com"
-
-      # Email account username
-      # With third party providers, this is usually the full email address.
-      # With self-hosted email servers, this is usually the user part of the email address.
-      user: "gitlab-incoming@gmail.com"
-      # Email account password
-      password: "[REDACTED]"
-
-      # IMAP server host
-      host: "imap.gmail.com"
-      # IMAP server port
-      port: 993
-      # Whether the IMAP server uses SSL
-      ssl: true
-      # Whether the IMAP server uses StartTLS
-      start_tls: false
-
-      # The mailbox where incoming mail will end up. Usually "inbox".
-      mailbox: "inbox"
-      # The IDLE command timeout.
-      idle_timeout: 60
-    ```
-
-    As mentioned, the part after `+` is ignored, and this will end up in the mailbox for `gitlab-incoming@gmail.com`.
-
-1. Uncomment the `mail_room` line in your `Procfile`:
-
-    ```yaml
-    mail_room: bundle exec mail_room -q -c config/mail_room.yml
-    ```
-
-1. Restart GitLab:
-
-    ```sh
-    bundle exec foreman start
-    ```
-
-1. Verify that everything is configured correctly:
-
-    ```sh
-    bundle exec rake gitlab:incoming_email:check RAILS_ENV=development
-    ```
-
-1. Reply by email should now be working.