Forum OpenACS Q&A: VERP?
"o The MTA on the OpenACS server will need to be able
to make use of extention address
Qmail, Courier, Sendmail, Postfix, and Exim are all
able to handle this. The handling of bounces will
use a simular configuration to TMDA
Since a lot of people here VERP and think qmail, It was trying to use wording that didn't associate the ideas with a specific method of delivering mail or a MTA.
Also I'm going to apply the VERP system wide (all messages delivered by the server and not specific to a list, notification, etc.)