Peter Loron wrote: > 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? configure your sendmail to use your ISP's mail server as a 'smarthost'.