If you are looking for a turnkey email management solution to handle
subscribe/unsubscribe requests and email list grooming then Mail
List King from Xequte might work well for you.

This is one of the more thorough email list management systems
I have seen. Mail
List King handles subscription requests via forms on your web site, it
handles unsubscription requests, and bounced messages. Interesting note: it
can handle subscribe/unsubscribe requests using synonyms such as remove, drop,
etc.
You can also use Mail
List King to blast email to your lists. It handles customization of
your emails, too, so you can send personalized emails to a large list. If you
have not used personalized email marketing, then Mail
List King will definitely improve your relationship with your
prospects and customers.
Mail
List King offers a very nice graphing feature so you can measure and
analyze the growth of your email lists. All in all, this is a very turnkey
email list manager and blaster. By default it supports Outlook, but it states
it can support other packages including Eudora through MAPI. Click here
for more info.