> Maybe you could use TOPICS

Doesn't this mean we need to include the TOPIC name in the SUBJECT tag? If
so this is not a valid option since we need full control over the Subject
content.

> subscribers (or to B, or to both)? I don't really understand
> your requirement fully, and you don't explain how you identify
> which group, A or B (or both) a subscriber qualifies for

It is a mass marketing E-mail. Recipients are selected from our CRM
database based on various criteria. We are using the list only as a
back-end to allow unsubscribes, so we're not worried about the user
messing things up. That is one reason we want to reset the options each
time we do a mailing.

--
Dave