Open Mail Relay
Erik Norgaard
norgaard at locolomo.org
Sat Aug 14 18:28:01 UTC 2010
On 14/08/10 15.29, peter at vfemail.net wrote:
>
> I have a machine running FreeBSD, sendmail and majordomo. I have someone who is on one of those majordomo lists complaining that they are receiving spam from me. The complainer says I have an open mail relay that I need to fix.
When somebody complains that they receive spam via your relay they must
the very least forward one of the offending mails to you so you can
study the header. If they deleted the message simply instruct that the
next spam mail is forwarded to you.
In the header you can check the Received headers to see if it actually
passed through your server first check ip & hostname, then see if the
message id appears in your logs. It is far to easy to forge a mail that
appears to come from your server or domain.
If so, the received fields will also show where the offending mail was
sent from so you can act on it.
If he's a subscriber to a list could it be that somebody send spam
through the list?
> I went to<http://www.abuse.net/relay.html>http://www.abuse.net/relay.html to test the machine using its IP address. Abuse.net gives a clean bill of health, saying relaying was denied in 17 separate tests.
>
> I've reviewed my mail logs for the past couple of days and I can't find any entries for any mail addressed to the complainer's domain name except mail that should have been sent.
>
> Is Abuse.net's test adequate to rule out an open mail relay problem?
I don't know about this site, but it should be easy to check your logs
for their connections and see what action is taken.
BR, Erik
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