Question : Sendmail does not deliver when email comes from an external server

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: [email protected]

If I send an email from the problematic server eg

> echo hello | mail [email protected]

then the email gets delivered to [email protected] (as you would expect).

However, if the email comes from an external source, eg I send an email to [email protected] 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

Answer : Sendmail does not deliver when email comes from an external server

Doing a "telnet mail.toptipper.com smtp" makes a connection to the smtp port of the server.  If it doesn't pick up and say hi then your mail server is either not running, or you have a firewall blocking it.  You're just using the telnet program to make a connection on the smtp port - you aren't telnetting to the telnet port (which no one uses any more anyway) - hopefully that makes sense?  You can actually use telnet to test any un-encrypted service as long as you know the right commands - pop3, imap, smtp, http, etc.  Its very useful.

So ya, make sure sendmail is actually running ("pgrep -fl sendmail" and "netstat -nlp|grep sendmail")and make sure you don't have a local firewall (iptables --list).  You'll see some basic iptables rules even if you aren't firewalled - but I'd try running "/etc/init.d/iptables stop" to bring down the rules just to test.  If the "netstat -nlp|grep sendmail" only shows "127.0.0.1:25" and not "0.0.0.0:25" then your sendmail is only listening on localhost and you need to edit /etc/mail/sendmail.cf and modify you DaemonPortOptions to not have "Addr=127.0.0.1".

Let me/us know what you find.