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Old 05-28-2004, 03:11 AM   #1
Registered: Jul 2003
Location: Norway
Posts: 65

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How can I tell if my sendmail is an open relay..

I thought my sendmail server where secure for open relay until I read about spoofing (hijacking of my domain name). Now I am paranoid again.

What log do I have to see and what do I have to look for to make sure that my sendmail server is not an open relay (did so many different things in webmin to make it work, so I am afraid that I have turned on something I shouldn't have or something.)

I check sendmail.log in /var/log and saw entries like this:

May 26 17:53:38 linux sendmail[29491]: i4QFraD3029491: ruleset=check_rcpt, arg1=
<>, relay=[], reject=550 5.7.1 <infobank76>... Relaying denied. IP name lookup failed []

May 28 05:33:41 linux sendmail[6734]: i4S3XeD3006734: ruleset=check_rcpt, arg1=<>, relay=[], reject=550 5.7.1 <nmyone19@hanma>... Relaying denied. IP name lookup failed []

May 28 05:33:41 linux sendmail[6734]: i4S3XeD3006734: from=<>, size=0, class=0, nrcpts=0, proto=SMTP, daemon=Daemon0, relay=[]
Guess the two top ones has been denied, but the bottom one looked like it went to

My webmin settings are as follows:

Local domains: Mydomain
Relay domains: Mydomain and subdomains

The rest would be standard I think...

And how quick are the relay guys anyway. From the log I see that they tried to relay allready before I knew my mail server where working. And it only took 30 minutes before my first junkmail arrived...

Last edited by Bjorkli; 05-28-2004 at 03:12 AM.
Old 05-28-2004, 03:35 AM   #2
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