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SMTP access rule testing

Postfix has several features that aid in SMTP access rule testing:

soft_bounce

This is a safety net that changes SMTP server REJECT actions into DEFER (try again later) actions. This keeps mail queued that would otherwise be returned to the sender. Specify " soft_bounce = yes" in the main.cf file to prevent the Postfix SMTP server from rejecting mail permanently, by changing all 5xx SMTP reply codes into 4xx.

warn_if_reject

This is a different safety net that changes SMTP server REJECT actions into warnings. Instead of rejecting a command, Postfix logs what it would reject. Specify " warn_if_reject" in an SMTP access restriction list, before the restriction that you want to test without actually rejecting mail.

XCLIENT

With this Postfix 2.1 feature, authorized SMTP clients can impersonate other systems, so that you can do realistic SMTP access rule tests. Examples of how to impersonate other systems for access rule testing are given at the end of the XCLIENT_README document.