Notifications

Email, in-app todos, and the rules that decide who hears about what.

Source

Concern	Location
Settings model	app/models/notification_setting.rb
Recipient resolution	app/services/notification_recipients/
Notification service entry point	app/services/notification_service.rb (~37K LoC)
Email mailers	app/mailers/, app/mailers/emails/, ee/app/mailers/
Todos	app/services/todo_service.rb, app/services/todos/
Email reply via mailroom	lib/gitlab/email/, config/mail_room.yml

Notification preferences

Each User has a global notification level plus per-group / per-project overrides:

• disabled
• participating (default)
• mention
• watch (everything)
• global (defer to upstream level)
• custom (per-event flags)

NotificationSetting rows store overrides; the resolver merges global + overrides per recipient.

Recipient resolver

NotificationRecipients::* walks an action (e.g. "merge request reopened") and computes the recipients. It considers:

• The actor (sender) — usually excluded from recipients.
• The notification subscribers (issue watchers, MR participants).
• The notification level for each.
• Mute / unsubscribe state.
• Confidentiality: confidential issues are gated to project members.

The resolver returns recipients grouped by notification reason ("subscribed", "mentioned", "assigned", etc.).

Mailers

app/mailers/notify.rb is the master mailer; specific events route to methods like new_issue_email, note_email, merged_merge_request_email. Each mailer renders an HAML template plus a text alternative under app/views/notify/.

Email reply

GitLab supports reply-by-email for issues, MRs, and notes:

• mail_room reads incoming mail (config/mail_room.yml).
• Gitlab::Email::* parses the body, extracts the reply token, and posts a comment.

Todos

Todos are an in-app inbox:

• Todo rows are created by TodoService (app/services/todo_service.rb) when a user is assigned, mentioned, or asked to review.
• Users see their pending todos in the "Todos" UI.
• Todos can be marked done, snoozed, or dismissed.

Push notifications

For mobile push (limited): Gitlab::PushNotifications. Optional, disabled by default.

Related

• Issues and work items — the biggest source of notifications.
• Source code management — MR notifications.
• Sidekiq jobs — email is sent asynchronously.