Enabling SASL authentication in the Postfix SMTP server

In order to enable SASL support in the SMTP server:

/etc/postfix/
main.cf:
    
smtpd_sasl_auth_enable = yes

In order to allow mail relaying by authenticated clients:

/etc/postfix/
main.cf:
    
smtpd_recipient_restrictions = 
        
permit_mynetworks 
permit_sasl_authenticated ...

To report SASL login names in Received: message headers (Postfix version 2.3 and later):

/etc/postfix/
main.cf:
    
smtpd_sasl_authenticated_header = yes

Note: the SASL login names will be shared with the entire world.

Older Microsoft SMTP client software implements a non-standard version of the AUTH protocol syntax, and expects that the SMTP server replies to EHLO with "250 AUTH=stuff" instead of "250 AUTH stuff". To accommodate such clients (in addition to conformant clients) use the following:

/etc/postfix/
main.cf:
    
broken_sasl_auth_clients = yes