Please make sure that the code of the subtasks of this task is deployed in the week of Sep 19th.
Background:
One wish of the German-speaking community's wishlist is T139962: When saving, be informed about mentions you sent (#9)
To fulfill that, the WMDE-TechWish implemented two opt-in features for notifications: Be notified when you successfully send out a mention and be notified when the system failed to send one of the mentions you wrote.
In some cases, however, it made more sense to change the mention code instead of sending out failure reports. These are the two instances, where we decided to go that way instead.