Milter-greylist

Hi,

I have an issue where some undeliverable messages sent back from
"postmaster@..." domains get greylisted for many hours (72, 96, etc).

I'm wondering how others deal with this?

I'd like those types of messages sent by users delivered back to them pretty
quickly so they know the recipient isn't contactable at that time (for
whatever reason). But I don't want to blindly not greylist postmaster@*.com
for example.

Thanks.

Michael.