Mailing list software

[Thomas Cameron]

Howdy All -

A friend of mine is looking to do a monthly or so e-mail blast to her
customer base, about 800,000 customers.  No, it is not spam.

I am trying to figure out the best mailing list software for this.  Of
course, mailman comes to mind, but it's really meant more for group
interaction, not a marketing type of list.

I need something that is going to be smart enough to automatically deal
with unsubscribing dead accounts and the like, and preferably has a
customizable web UI for account management.

Anyone use any cool mailing list for Linux that meets these needs?

-- 
Thomas