Email Newsletter modification

[squishi]

Does anybody know of a good email newsletter add-on for vbulletin?

It should
- send out emails to the members in both html and text format
- offer an opt-out link in the email with which users can easily opt-out of the newsletter emails.

I know I could just use the vb email system for this. But it does not offer an easy way for people to opt-out. Opt-out should be done just by clicking a link in the email, and not by having to log in and change the settings.

I can also pay for this mod, but I thought I'd ask for a free one, first.