user email

Hi,

Hoping someone can advise. I need a module(s) that can send an email to a new user x number of days after they register to the site.

Essentially, I have been tasked with creating a membership site with different levels of membership from basic to premier. When a user signs up as a basic (normal authenticated) user I need the site to email them automatically (ideally via cron) after a week if they haven't signed up to become a premier member.

I've looked at the newsletter (simplenews) with scheduler, messaging, bulk operations, rules and yet I'm still drawing a blank.