what is a good list management software?

hello, I have a friend that has a real estate marketing business. He has huge lists of emails that he sends out newsletters to on a regular basis. He basically needs a list manager to help with the checking or verifying of the email accounts, automating list management when emails get returned as bad or unknown emails, also to automate when a person wants to unsubscribe. I looked at a few websites like lsoft.com and ima.com majordomo doesn't seem like it's suited to this...or at least that's my impression. Is this correct? Thanks, Oskar ps. sorry for being a bit off topic...but I do regard this list as having very knowledgeable people ...so I am interested to see what recommendations come from this.