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Postfix SMTP AUTH support for relayhost
by Ben Franske 
Tonight I changed my relayhost for my outgoing home mail server to one that requires me to use SMTP AUTH so I needed to modify my main.cf on the outgoing server as follows.
Added the following settings to /etc/postfix/main.cf:
smtp_sasl_auth_enable = yes
smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd
smtp_sasl_security_options =
Create /etc/postfix/sasl_passwd as follows:
my.mail.relay.net username:password
Because the password is in cleartext make it root only:
# chown root:root /etc/postfix/sasl_passwd && chmod 600 /etc/postfix/sasl_passwd
Create the hash file:
# postmap /etc/postfix/sasl_passwd
Make the hash file world readable:
# chmod 644 /etc/postfix/sasl_passwd
Reload the Postfix config:
# /etc/init.d/postfix reload
09/06/05 08:57:16 pm, 
4 comments
Make the hash file world readable:
# chmod 644 /etc/postfix/sasl_passwd
But shouldn't that be:
chmod 644 /etc/postfix/sasl_passwd.db
???
When I do the postmap command you show it doesn't alter the mother file, but it makes a .db file.
smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd to smtp_sasl_password_maps = /etc/postfix/sasl_passwd.db or something similar. I think that my original method hashes the file on demand instead of accessing a pre-hashed file. Secondly, you have to chmod the sasl_passwd.db, and not sasl_passwd. ( i'm talking about the second chmod).
And, if you chmod 644, then you'll have security problems, because the .db file IS NOT encrypted, and anyone can read the file with a simple editor.
So, the solution would be to chown it to postfix:postfix and chmod 600 the sasl_passwd.db.
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