Sendmail / alias issue

[Nathan Vidican]

I know there might be a better sendmail/related mailing list to send this to, 
but figured I'd drop it here and give it a shot - sorry for the cross post, but 
I subscribe to -questions so figured it'd be okay and beneficial to other users 
too. Anyhow, on with the problem:

I have an entry like this in /etc/mail/aliases:

someolduserwhoquit:	550:"The user you have attempted to send mail to no \
			longer exists on this system, please see\
			http://www... for details or a new contact"

(not exact; in alias file it's all on one line with no \ )

alias works exactly as expected; when someone sends a message to 
someolduserwhoquit at wmptl.com, it bounces their message back with the error 
string I quoted. The problem then, becomes SPAM (lol - when is SPAM NOT a 
problem eh?).

example:
  - (faked) from: somefakeid at yahoo.com
  - sends a message to someolduserwhoquit at wmptl.com
  - tries to bounce message back, in-turn getting message bounced back to
    our postmaster saying 'no valid user here for somefakeid at yahoo.com'

So, to the question part... how can I setup an alias to either ignore the 
bounce-back it gets, (ie to blindly send the bounce itself), or is it possible 
to specify a different from address on our server's end so when/if the other 
receiving server doesn't have a valid from address it just drops the reply on 
our end, like so:

  - our server gets mail faked from 'joeblow at hotmail.com' to 
someuserwhoquit at wmptl.com
  - our server bounces said message back to joeblow at hotmail.com with 
notification that 'someuserwhoquit at wmptl.com' points to an old/invalid address, 
our server sends from 'noreply at wmptl.com'
- their server (this case hotmail), bounces back saying 'hey - don't have a 
joeblow@ here' to noreply at wmptl.com
- noreply at wmptl.com just drops any incoming message (/dev/null kinda deal)

Is this possible? Or should I perhaps be seeking a better way to do this all 
together? I'm getting some 30+ Postmaster reply errors a day and it's getting 
really annoying, however I do need to send some sort of error/notification to 
valid (real) emails sent to the wrong address. In some cases an employee has 
moved, transferred, quit, or retired and a different person has taken their 
place - as such I need like a grace period and a better way to do this. Any 
ideas/thoughts/suggestions welcomed.


-- 
Nathan Vidican
nvidican at wmptl.com
Windsor Match Plate & Tool Ltd.
http://www.wmptl.com/