Sender verification

The main mail protocol, SMTP has a hole in it: there is no verification of the sender. This allows spammers and others to pretend to be anyone they want. But with a little bit of effort, sendmail (for example) can be configured to use SSL and user verification. That way you can have your own SMTP-server accessible anywhere, without open relay.

There are also several new protocols for fixing SMTP problems:
 * SPF
 * SMTP authentication

= Set it up = Now you do not want anyone to be able to use your mail server as spam-catapult. So you need sender verification in your postfix service.

Make sure your authentication service is running: /etc/init.d/saslauthd status has to deliver running In /etc/postfix/main.cf, set smtp_sasl_auth_enable = yes smtpd_sasl_auth_enable = yes Restart Postfix /etc/init.d/postfix restart To prove it works, use kmail. Set "server requires password" in the outgoing mail account.

= TroubleShooting = If you get an error message like Error: authentication failed: generic failure Make sure the saslauth daemon is running: /etc/init.d/saslauthd restart

= See also =
 * http://www.jonfullmer.com/smtpauth/