Enabling SASL

In order to turn on authentication in the Postfix SMTP server, add the enable parameter to your main.cf file:

smtpd_sasl_auth_enable = yes

In addition, some older email clients don’t follow the SMTP authentication protocol correctly. The specification calls for the server to list its supported mechanisms after the keyword AUTH followed by a space. These clients expect to receive *AUTH followed by an equals sign. Postfix allows you to accommodate them by setting the following parameter:

broken_sasl_auth_clients = yes

By setting this parameter, you tell Postfix to advertise its SMTP authentication support in the nonstandard way as well as the standard way. This option is perfectly safe to use since it doesn’t interfere with other mail clients, and the nonstandard ones will now work as well.