sendmail on ubuntu (9.10) machine "stopped" sending mail

Solution 1:

I believe that you need to change the hosts file to state:

127.0.0.1    localhost
127.0.0.1    doron-desktop

The 127.0.1.1 was introduced with Ubuntu Edgy. But some applications look for the host name to match 127.0.1.1. Sendmail is one such application. You can keep the 127.0.1.1 if you want to stick with the new standard but be sure to add 127.0.0.1 doron-desktop.

Also note the following in your error log:

ruleset=check_rcpt

After which you are told that your doron-desktop domain doesn't exist. There are different files that will allow you to set your domain name. Try setting the domain name in the following areas:

/etc/hosts
/etc/resolv.conf
sendmail conf files

You definitely need to convince sendmail that you have a domainname and that it's FQDN (even though it's not). If you have a domain name registered use (in your hosts file):

doron-desktop.somedomain.com

The server won't care that public dns doesn't point to your desktop computer. That being said, email server that you send email too might (or will) care that your desktop server is sending email on behalf of whatever domain name you put in the hosts file and may either block the emails, return them, or blacklist them (blacklisting won't happen if your just testing - you'll need to send out thousands of tests).

Solution 2:

It sounds like at some point, sendmail is now checking to see if you domain is resolvable.

In that case, you can get sandmail to accept unresolvsble domains by rebuilding sendmail.cf. This involves updating sendmail.mc with the following:

FEATURE(`accept_unresolvable_domains')dnl

And then rebuild sendmail with the make command and restart sendmail:

/etc/mail/make

Be sure to have a backup of sendmail.mc and sendmail.cf before you proceed.