My mail server got hung up for a while because of an (unrelated) NFS problem, and a bunch of incoming email got queued up. When I rebooted the server, postfix got started before ypbind, so all of the queued mail (56 emails in my case) bounced with an "unknown user" error. Needless to say, this is a bad thing. My fix: change "use logger dns" in /etc/init.d/postfix to "use logger dns ypbind". Just to be sure, I also set "unknown_local_recipient_reject_code = 450" in /etc/postfix/main.cf (it was set to 550 before, which permanently rejects the mail).
I have updated the postfix init.d file in portage accordingly. Changing the reject code to 450 is not something that I plan on changing by default though. That can make for a very large queue if your mail server gets spammed. Anyway, thanks for the heads up on the startup problem.
