Has anyone found an email marketing/list service that would allow you do some sort of querying of custom fields of each user or tag each e-mail address to indicate multiple categories? The point of this would be I want to send e-mail 1 to only people who have purchased both products A and B, but not if they purchased product C. And another e-mail, 2, may be sent to those who purchased any of the three. Every service I've tried only lets an e-mail address occur in one category/list, and disallows duplicates for obvious reasons going into multiple lists. I can do it with PHPList, but I've had very little luck getting many mails received with it. Thanks.