Web forum software with email recommendation

[Neal D. Becker]

Can anyone suggest a package to implement a web forum that does email
gateway?  I tried phpBB which is very nice, but it appears that users can
only post via web.  I want to bi-directional gateway email also, similar to
yahoogroups.

(I tried google, but it seems to be hard to find a combination of words on
this subject that has any probability of matching the right topic)