Enable port 587 Postifx

Please note if using plesk this needs to be turned on in the mail server settings under the plesk GUI, tick 'Enable message submission' (this should work without changing the below as it'll do that for you)


vi /etc/postfix/master.cf


Add or uncomment the below
submission inet n - n - - smtpd
-o smtpd_sasl_auth_enable=yes
-o smtpd_client_restrictions=permit_sasl_authenticate d,permit_mynetworks,check_relay_domains,reject


Sometimes you may have a login issue.
Change smtpd_tls_security_level=encrypt to =may