Im trying to set up my box to send emails thru a relay, if the sending user = x.

For example:
I have 2 boxes, example,com and relay example,com
example,com sends all emails directly to recipients, unless email originated from userx at example,com, then it should send it thru relay,example,com

I know how to set up mailertable to do this based on recipient domain, but like I said I need this based on sending user.

relay,example,com is set up to relay emails correctly from example,com, so thats not a problem.

Thanks in advance to anyone who can point me in the right direction.

PS , instead of . since I am thought of as a spammer