If I allow others to send emails over my server the postmaster receives all those mail errors, now I don't care if an email I haven't send of doesn't arrive ... is it possible to send the postmaster notify to just the sender of the email and not the postmaster user on the server ?

So let's say I permit user X to relay email. Now he sends of an email with a wrong address, etc. I as the system admin don't really care about that in general and don't want to receive his postmaster notifies, how would I need to change the sendmail.mc or something other that only the user who sent the email - in this case user X receives the postmaster notify?

BTW, as MTA I'm using sendmail 8.12.5

Hmm. Isn't that in /etc/aliases?

I wouldn't like to disable the whole postmaster account ... I don't think that's a good idea! Just those annoying postmaster notifies. Disabling postmaster would be:

postmaster: /dev/null

in the aliases file!

Ah. OK. Round two :-]
How about "#O PostmasterCopy=Postmaster" then?

Nope that's also not the solution ...
None of those is the solution!