Way to automatically block SASL LOGIN attacks?

I added for postfix section into the jail.conf; But fail2ban has a many options inside [couriersmtp] - [sasl] - [dovecot] I didn't add on this sections. Just I added postfix menu side.
Also Postfix I did
[Postfix]
enabled = True

 

I can display easly on mail.log, Postfix has been sending mail but gmail is rejeting "doesn't resolve to address and name or service not known" messages and never finishing " SASL login authenctication failed : authenctication failure.