Outbound SMTP Simple Mail Transfer Protocol (A message send protocol) authentication is achieved by extending the ISP SMTP host entry in either the Outbox A temporary storage location used before delivering messages to another mail server./Delivery page or a Remote Domain A domain type that is used to send SMTP mail for a specific domain to a pre defined location rather than to the internet in general./Delivery page. Outbound authentication is not available when using MX delivery options.
The format is:
host address[:host port][;login See: Sign In id;password]
e.g. mail.isp.com:25;fred;mypassword
bracketed items are optional.