**As** a user of OpenProject
**I want to** get only one notification when I am @mentioned. Currently there are scenarios when I get a @mention email first and later another email reminder with exactly the same content.
**so that** I receive less email spam.

**Acceptance criteria**

* @mentions emails are sent immediately based on the user's email reminder settings (no change). Begin of the insertion

End of the insertion Begin of the deletion
End of the deletion * In case an email for an @mention is already sent Begin of the insertion(requires the userEnd of the insertion Begin of the deletion and there is no other reasonEnd of the deletion to Begin of the insertionhave checkedEnd of the insertion Begin of the deletion send out an email reminderEnd of the deletion the Begin of the insertion'Immediately when someone @mentions me' option inEnd of the insertion email Begin of the insertionnotifications)End of the insertion Begin of the deletion reminder is not sent. In other words: Email reminder are only sent for new information. Not forEnd of the deletion notifications Begin of the insertionwith `mention` as the topmost reason are not included inEnd of the insertion Begin of the deletion which already triggeredEnd of the deletion an email Begin of the insertionreminder mail. 


**Technical notes**

* The column `reason` on the `Notification` model states the reasons.

* The column `mail_alert_sent` on the `Notification` model states whether a direct mail has been sent out. 

* With those two pieces of information combined, the specified case can be identified and suppressed.End of the insertion Begin of the deletion reminder.End of the deletion