sendmail won't send

I'm trying to get sendmail working so I can test out mail functions in PHP. I've got it installed and running and it is receiving the mail requests... However it's not sending anything. Here's a log from the mail log:

Code:

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May 16 17:05:37 [sendmail] gethostbyaddr(192.168.0.125) failed: 1

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I'm pretty sure that's holding it up, especially since the following is a running process:

Code:

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26718 ?        S      0:00 sendmail: ./l4HNqkXr025759 gmail-smtp-in.l.google.com.: user open

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Never gets sent, never arrives in my GMail inbox...

This means that the firewall could not find the listed address.
If that machine is in your domain then you need to make sure that
you have the appropriate DNS records for it. Try nslookup to see
if you could get the address resolved.

How exactly do I do that?

You use nslookup. nslookup <ip address> returns the resolved name. You need a host file that points that hostname to that IP address. You basically just need to set up your DNS correctly. Do a man on nslookup for additional options or use <Linux> - Google Search to help you out. There are better how-tos explaining this than myself explaining it. I tend to loose people when trying to explain something in detail

You might be successful by simply putting an entry for the host '192.168.0.125' in the sendmail host's /etc/hosts file. That may be sufficient to satisfy the reverse lookup.

--- rod.