Hi, we have postfix setup on a centos box as an smtp relay, so I setup relay_domains and transport maps to relay emails addressed to our domains to our mail servers. We are using postini as anti-spam, so I'm not really worried about spoof emails. However, I forgot to add a rarely-used domain to the transport map, and an email addressed to that domain bounced. We received a bounce email, but this is what I'm confused about. The email address that received a bounce notification is support@ourdomain.com, which is actually where we want it to go, but I never set up that email address. I set the postmaster alias in /etc/alias to be my personal email address, and in main.cf there are no bounce configuration lines (which I'm assuming means it uses the default postmaster account). I'm confused about how it got sent to the support email address? Googling just keeps showing me the alias files, it doesn't really explain how postfix could be sending it to that particular email address. Thanks for any light that can be shed on this matter!

Have a look in the /etc/aliases
It should have a line like
support: postmaster
that tells postfix to redirect email sent to support (and many others) to postmaster.

thanks for the reply.
I've already configured /etc/aliases. This is my config for aliases:

mailer-daemon: postmaster
postmaster: myemail@domain.com
root: myemail@domain.com

Did I do this incorrectly? Do these have to be system accounts, and if so, how can I have it so that alerts sent to postmaster are forwarded to my email? And this still doesn't explain how the emails are getting sent to support@domain.com when the default bounce should be sent to postmaster??

edit:
also, the rest of /etc/aliases hasn't been changed, so it's still support: postmaster

Have you tried a
service postfix reload,
service postfix restart or a
full system restart
after modifying /etc/aliases ?

I thought I did, as well as newaliases, but I'll run those commands again. In the meantime, I just want to confirm that you can in fact write out the email address for the postmaster: alias? Everything I see online shows the postmaster: alias set as a local system account, and then forwarding the emails? This kind of confused me, but is this doable?

Normally, yes.
If you have a local user named bob
you can have a line similar to
postmaster: bob
in /etc/aliases
in order to have all the emails sent to postmaster to bob.
But I have never tried it.

Besides, normally you just need to launch
service postfix reload
Not all three actions.

That's what is confusing to me...how/why did the notification email get sent to support@ourdomain.com in the first place??? I sent an email that I knew would bounce, as a test, and I haven't received a notice yet. I sent it yesterday, the last one took about 3-4 days to come so it may take that long for this as well. I'm just confused by that email. I haven't received anything at all at my personal address, which is what I set the postmaster alias to be!