Hi. I think it would be super helpful to have the ability to upload a "do not mail" list when I select the list(s) I want to email to. For example, I want to email a few lists an invitation to an event. But I've already emailed them twice already and have a bunch of RSVPs for the event. I don't want these RSVPs to get another invitation, so I want to purge them from my third invitation mailing.