Add SASL configuration options to Webconfig
These days, when relaying through an ISP or SMTP service provider you are required to use SASL through port 587 (or sometimes 25 or 2525 etc). This should be a webconfig option to enable SASL can select the port used. There is a howto at https://www.clearos.com/resources/documentation/clearos/content:en_us:kb_howtos_smtp_authentication_to_isp but you may also need to set smtp_use_tls = yes
in /etc/postfix/main.cf