I'm hoping someone might be able to help me with a bit of a relay issue I've been experiencing for a while.
I am running Virtualmin Pro, with Postfix 2.2.10 under CentOS 4.6 (Final), and as far as I can tell it is NOT an open relay. I used http://www.rbl.jp/svcheck.php to test this. Way back when I used to use the RBL telnet to tcp/25, though from what I can tell that is no longer operational and these tests seem similar.
In any case, the URL I mentioned passes all tests confirming that I am not an open relay. However I have a bunch of emails in my mail queue that as far as I can tell shouldn't be there - the destination are all external to my server.
Looking through the mail logs, it seems that the common factor is that all emails, when submitted to my server, have no 'from' address. The actual log shows: from=<>
I'm not sure how to stop these emails from being submitted to Postfix?
Any suggestions/thoughts would be most welcome.