I subscribed to a mailing list today. I had to wait until the validation email passed through the greylist daemon [1] on my system, but once that happened, I can start replying to the list.
Only the first post I made didn't go through. There was no error reported. There was no bounce message. Nothing. I checked to make sure I was using the address I signed up with (I did) and the filters on my email program were correct (they were).
I then checked the logs and behold:
Oct 30 19:07:41 brevard postfix/smtp: 023E22EA679B: to=<XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX>, relay=XXXXXXXXXXXXXXXXX[XXXXXXXXXXXXX], delay=4, status=deferred (host XXXXXXXXXXXXXXXXX[XXXXXXXXXXXXX] said: 450 4.2.0 <XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX>: Recipient address rejected: Greylisted, see http://postgrey.schweikert.ch/help/XXXXXXXXXXXXXXXXXXXXX [2] (in reply to RCPT TO command))
Ha! I'm being greylisted right back! This is the first time I've noticed my outgoing email being greylisted. I find this amusing.