Tuesday, January 10, 2012

Accepting Unresolved Domains in Sendmail

If you want to read your email messages from your local machine, you will need some packages to be installed:
  1. Fetchmail
  2. MTA (Mail Transfer Agent), it would be Sendmail in Slackware's default installation
  3. MUA (Mail User Agent), it could be pine or mutt in Slackware
If you configured fetchmail properly, then in short time, you will be able to receive your messages through pine and mutt for offline view.

Sendmail by default will reject an email from unresolved domains, because it is suspected as a spam. However, if you have difficulties with your DNS server, it might treat normal messages as unresolved as well. So, how do i configure Sendmail to get all email messages, including from unresolved domains?

You must edit Slackware's sendmail configuration file, rebuilt it, and put the new configuration file into the proper place and restart Sendmail. Here's how to do it:
  • Open up /usr/share/sendmail/cf/cf/sendmail-slackware.mc
  • Add this line FEATURE(`accept_unresolvable_domains')dnl
  • Copy the file to /usr/share/sendmail/cf/cf/config.mc
  • Go to /usr/share/sendmail/cf/cf/
  • Execute sh Build config.mc
  • Copy config.cf to /etc/mail/sendmail.cf
  • Restart sendmail: /etc/rc.d/rc.sendmail restart
You will now receive any incoming email messages through your inbox, including from spammers, so please use this feature wisely.