Im pretty sure that you can't send emails with SPRocs, I could be wrong but it doesn't sound like this would be the place to write this sort of logic. Seems that the best thing to do is to retrieve all customer information as one DB call and then process the email send out in your ASP code.

Depending on how many customer records you will have to update and the regularity of this type of action then its your call whether you batch these update statements together and run send them all over the wire to the db or not.