I am a newcomer to Postfix, so this is probably an easy question to answer.

Postfix is acting as a mail gateway to an internal mail system, and I'm
using relay_recipients_map to block unknown recipients at the gateway
(instead of allowing the messages through to the internal system and
then generating a non-delivery report). This is working just fine, but
I'm interested in changing the text that Postfix returns when an
invalid/unknown recipient is submitted. I'm almost positive I saw
reference to a Postfix parameter for this, but can't find it now. Does
anyone know the name of the parameter that would allow me to change
this text?

TIA

--
Scott Lowe