[CentOS] Sendmail failing on home machine

Peter Loron peterl at standingwave.org
Wed Nov 7 06:27:12 UTC 2007

I have a CentOS 5 machine at home, behind a NAT gateway. Among other  
things, I'm running mdadm in monitor mode to alert me to RAID  
failures. I want it to send messages to my main email address. Any  
messages I send from the home CentOS box to that email address are  
being rejected with this error:

Deferred: 451 Could not complete sender verify callout

My understanding is that the destination mail server is trying to  
connect back to the source email host via SMTP as an anti-spam check  
and is failing.

My external IP is set up with a dynamic DNS entry, so I guess I could  
set up an MX record and actually receive mail on the home box, but I  
don't want to deal with the security issues or the spam.

Any suggestions for allowing sendmail-dependent apps running on the  
home machine to be able to send mail?



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