Postfix Authentication
Postfix handles authentication separately for sending (smtp) and receiving (smtpd) mail.
Receiving Authenticated Mail
Sending Authenticated Mail
The basic configuration for outgoing mail is:
smtp_sasl_auth_enable = yes smtp_sasl_security_options = noanonymous smtp_sasl_password_maps = lmdb:/etc/postfix/sasl/sasl_passwd
Create a SASL passwd file like:
[smtp.gmail.com]:587 [email protected]:wwwwxxxxyyyyzzzz
Note that GMail specifically provides 16-character tokens. This is not a system requirement.
Run postmap /etc/postfix/sasl/sasl_passwd and a hashed file will be produced. If your postmap(1) does not use LMDB, replace the lmdb: with whatever algorithm was compiled into the distribution.