Can any postfix guru assist me determine how emails are still being sent via my server from unauthorized sources?

Posted by Dave on Server Fault See other posts from Server Fault or by Dave
Published on 2011-01-07T15:52:54Z Indexed on 2011/01/07 15:55 UTC
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Hi all,

I'm getting a little concerned as I run a small server hosting a number of websites and manage the email for a few dozen people.

Just recently though I've had a couple of notifications from spamcop alerting me that spam has been sent from my server, and when I have a look over the logs from time to time I can indeed see that there are many repeated attempts of mail being sent from my server. Most of the time it gets knocked back from the destination servers but sometimes its getting through.

Unfortunately I'm not linux or postfix expert, I can get by but had though I had my machine locked down quite securely, I don't allow relaying, when I check the online DNS/MX tools they tend to report my server as being OK so I'm not sure where to take it now and hoping someone might be able to throw me a few pointers.

I get lots of entries like this in my MAIL.INFO log

Jan  2 08:39:34 Debian-50-lenny-64-LAMP postfix/qmgr[15993]: 66B88257C12F: from=<>, size=3116, nrcpt=1 (queue active)
Jan  2 08:39:34 Debian-50-lenny-64-LAMP postfix/qmgr[15993]: 614C2257C1BC: from=<[email protected]>, size=2490, nrcpt=3 (queue active)

and

Jan  7 16:09:37 Debian-50-lenny-64-LAMP postfix/error[6471]: 0A316257C204: to=<[email protected]>, relay=none, delay=384387, delays=384384/3/0/0.01, dsn=4.0.0, status=deferred (delivery temporarily suspended: host mx.fakemx.net[46.4.35.23] refused to talk to me: 421 mx.fakemx.net Service Unavailable)
Jan  7 16:09:37 Debian-50-lenny-64-LAMP postfix/error[6470]: 5848C257C20D: to=<[email protected]>, relay=none, delay=384373, delays=384370/3/0/0.01, dsn=4.0.0, status=deferred (delivery temporarily suspended: host mx.fakemx.net[46.4.35.23] refused to talk to me: 421 mx.fakemx.net Service Unavailable)

then there tends to be connection timeouts, so from what I see even though I had relaying disabled.. something is getting by and trying to send..

So if you can help that will be greatly appreciated, and any further logging/config info I can supply.

Thanks

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