I believe in other trackers this is achieved by having a user A "watch" another user B, so that all the notifications going to user A are also sent to user B.

The policy about who should be able to se the "watch" flag is to be investigated

There are two approaches here:

1. User A watches User B - in this case User A will probably get all mails to user B that user A has access to??

2. User B sets an Out-Of-Office like setting, where he delegates user A to retrieve all emails destined to him/her. In this case, all emails that would have been targetted to B will also be sent to A. Potentially such emails will have A on the "To" field and B in the "Cc" field.

a. Emails like password resets must not honor such delegation.

b. Delegation from a disabled user to enabled user, should result in the enable delegate receiving the email, but the disabled original user not receiving the email.

Hm, your answers go into a slightly different direction than what I wanted. There's currently the possibility to auto assign issues (based on settings for the project internal categories) to some mantis user. He's notified and the report gets the assigned status. So I'm only talking about this mechanism. This would prevent new issues from being stalled until the other person comes back from vacation or whatever. And since the issue is assigned to that delegation user he get's the e-mail notifications for that issue automatically.

I have a Holiday plugin which one can try

Latest vesrion of that plugin is under:
http://www.mantisbt.org/bugs/view.php?id=11080

cas, you have attached version 0.96 at 0011080
The version attached at the current issue 0011178 is 0.97
Do you agree?

If so, I will remove the attachment Holidays.zip and attach it as Holidays097.zip at 0011080

Atrol,
yes, that should be the way forward.
Thanks for cleaning my mess.