gitlab-org--gitlab-foss/doc/development/emails.md

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Working with email in development

Ensuring compatibility with mailer Sidekiq jobs

A Sidekiq job is enqueued whenever deliver_later is called on an ActionMailer. If a mailer argument needs to be added or removed, it is important to ensure both backward and forward compatibility. Adhere to the Sidekiq Style Guide steps for changing the arguments for a worker.

In the following example from NotificationService adding or removing an argument in this mailer's definition may cause problems during deployment before all Rails and Sidekiq nodes have the updated code.

mailer.unknown_sign_in_email(user, ip, time).deliver_later

Sent emails

To view rendered emails "sent" in your development instance, visit /rails/letter_opener.

S/MIME signed emails cannot be currently previewed with letter_opener.

Mailer previews

Rails provides a way to preview our mailer templates in HTML and plaintext using sample data.

The previews live in app/mailers/previews and can be viewed at /rails/mailers.

See the Rails guides for more information.

Incoming email

1. Go to the GitLab installation directory.

2. 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:

   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. This %{key} should be included in its entirety within the email
     # address and not replaced by another value.
     # For example: emailadress+%{key}@gmail.com.
     # The placeholder must appear in the "user" part of the address (before the `@`). It can be omitted but some features,
     # including Service Desk, may not work properly.
     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
   
     # Whether to expunge (permanently remove) messages from the mailbox when they are deleted after delivery
     expunge_deleted: false
   

   As mentioned, the part after + is ignored, and this message is sent to the mailbox for gitlab-incoming@gmail.com.

3. Run this command in the GitLab root directory to launch mail_room:

   bundle exec mail_room -q -c config/mail_room.yml
   

4. Verify that everything is configured correctly:

   bundle exec rake gitlab:incoming_email:check RAILS_ENV=development
   

5. Reply by email should now be working.

Email namespace

As of GitLab 11.7, we support a new format for email handler addresses. This was done to support catch-all mailboxes.

If you need to implement a feature which requires a new email handler, follow these rules for the format of the email key:

• Actions are always at the end, separated by -. For example -issue or -merge-request
• If your feature is related to a project, the key begins with the project identifiers (project path slug and project ID), separated by -. For example, gitlab-org-gitlab-foss-20
• Additional information, such as an author's token, can be added between the project identifiers and the action, separated by -. For example, gitlab-org-gitlab-foss-20-Author_Token12345678-issue
• You register your handlers in lib/gitlab/email/handler.rb

Examples of valid email keys:

• gitlab-org-gitlab-foss-20-Author_Token12345678-issue (create a new issue)
• gitlab-org-gitlab-foss-20-Author_Token12345678-merge-request (create a new merge request)
• 1234567890abcdef1234567890abcdef-unsubscribe (unsubscribe from a conversation)
• 1234567890abcdef1234567890abcdef (reply to a conversation)

The action -issue- is used in GitLab as the handler for the Service Desk feature.

Legacy format

Although we continue to support the older legacy format, no new features should use a legacy format. These are the only valid legacy formats for an email handler:

• path/to/project+namespace
• path/to/project+namespace+action
• namespace
• namespace+action

In GitLab, the handler for the Service Desk feature is path/to/project.

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