Sendmail doesn't deliver when email comes from external server

[sportspunter]

Hi there,

I've had my servers setup for years, and working well. But I've recently been making some dns and other changes (like trying to install milter), and now I've run into a strange problem.

It's a Fedora Core something server running the latest sendmail and bind.

my /etc/aliases/file contains an entry like:

editor: myemail@myisp.com

If I send an email from the problematic server eg

> echo hello | mail editor@problemserver.com

then the email gets delivered to myemail@myisp.com (as you would expect).

However, if the email comes from an external source, eg I send an email to editor@problemserver.com from my PC, then the email does not get delivered. In fact there is not even an entry recorded in /var/log/mail (nor in /var/log/*), not an error message to be found.

Does anyone have a suggestion for me to look into?

thanks

 

[elgrandeperro]

First, understand how your old email routing works.
Look at any old delivered message in full header mode.

What you want to see are the last few hops (toward the top)
and see what MTAS it traverses. The last one better be yours.


Look for MX records for problemserver.com. Or look for a wildcard MX record for the whole domain. These should point to your server (or some relay that knows how to route mail to your server, which appears on the old header list)

I usually do this, from any internet connected host:

nslookup
>set type=mx
>problemserver.com

Should return mx records for your host.
If wildcarded (use a * in MX record)
nslookup
>set type=mx
>lskjflsfj.problemserver.com

should also work, incredibly. Of course mail to @lskjflsfj.problemserver.com will bounce.

eugene