Open Mail Relay

Erik Norgaard norgaard at
Sat Aug 14 18:28:01 UTC 2010

On 14/08/10 15.29, peter at 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<> to test the machine using its IP address. 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'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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