OOT: Mail rejected with bogus helo

Matt Kettler mkettler at evi-inc.com
Wed Apr 16 15:48:30 IST 2008

Budi Febrianto wrote:
> Dear All,
> I know this OOT, but because many sendmail experts in here, I give it a 
> shot.
> I'm using sendmail-8.13.8-2.el5 with MailScanner 4.65.3.
> Whenever my users sent emails to certain domains, it will rejected with 
> this error.
>  >>>>>
> 553 yyy.yyy.yyy.yyy rejected due to spam, contact 555-505-5555 (bogus 
> helo xxx.xxx.xxx.xxx)
>  >>>>>
> I'm not sure what happen, because I don't have the same problem with 
> others domain.

Your system is issuing a HELO in IP format, which is RFC compliant, but some 
view this as a sign a system isn't properly configured and will refuse mail from 
such systems.

However, more troublesome is your system is issuing a HELO in IP format using a 
private-range non-routable IP, This is blatantly bogus when 
communicating with hosts outside your network, as those hosts will never be able 
to route to and reach your server. (The original intent, although 
outdated, is for the HELO to be usable as a hint for where to return mail to if 
DNS fails to generate a MX or implicit MX record. Generating private IPs here is 
clearly contrary to that.)

Ultimately, it's up to the administrator of the system you're trying to contact 
to tell you why he's filtering you. Those are purely guesses on my part, based 
on looking at the HELO's your server issued, and general knowledge of what some 
admins do for filtering that not everyone does.

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