ok, here is our usage scenario. We have a client that has 8 different mailing lists. Some users are on multiple lists. We also create and modify all mailing lists and users via API's in our CMS.

Occasionally, this user wants to send out an email blast to everyone. This could lead to multiple people getting multiple copies of a single email. This is how we've had things setup and it's worked well until this point.

So at this point, we are wondering if it's possible to go a different route, and create 1 master list, with each user having tags (i believe this is something systems like mailchimp can do). In this setup, we could just say "send email to users tagged with list 1 and 3" or "send to all users". Usings tags would also greatly increase our flexibility with mailing lists,

The only other option i see at this point, is going completely manual via API's, dynamically creating lists, adding the appropriate users, sending, then deleting the original list. BUT i'm assuming this will cause it's own problems because of bounce back tracking and so forth?

Thank for any help / suggestions anyone can offer :-)