Forum OpenACS Q&A: Response to Help on missings bboard alerts: add-alert, alert-disable, alert-reenable

Take a look at the notifications package.  It does support
this (forums on dev.openacs.org uses it).

see http://dev.openacs.org/notifications/manage
and http://dev.openacs.org/forums/forum-view?forum_id=14013
for examples.