Membership site with integrated newsletter

I am looking for a solution that will require members to receive emails like POF does. At POF, if you unsubscribe from their email, your account is ALSO automatically terminated. I am looking for that kind of solution preferably that will work for WordPress. I plan of developing an ad revenue site with some free software downloads, but the stipulation will be they will have to receive my newsletters and emails so I can market the mess out of them