Do you know a good and free newsletter system written in php that allows users import/export from database or text files, store multiple fields for every user (like name, surname...) and create users groups?
I've tried Listmessenger, but it's not completly free, and CcMail but it's not very good for me...
Even tho you have discounted Listmessenger, I have set it up for numerous companies (with the purchase of a $49 cdn dollar license - for over 200 users!). They have been very pleased, as the software is simple enough for most users, and advanced enough to get the job done (that you require). I have only had good feedback about the software, where otherwise other software created a large learning curve and did not work exactly as well.
I would recommend giving it another try, and $50 cdn dollars is not exactly a fortune for advertising, plus you can use it free for under 200 users (some features missing of course, but I assure you its well worth it).
Otherwise, I have tried phplist.com, but I have found it to be confusing for most users. But try it if you want: http://www.phplist.com