we are re-organizing our address list and will start using segments. Is there a way, once we prepare a new campaign and assign it to be sent to one specific segment, to create a suppression list only to the segment, instead of to the entire list?
It is not a real suppression list, but you could let subscribers "unsubscribe" by changing the status of the custom field on your preferences page. IE: if you send to everyone who has the checkbox field "newsletter" selected, in the preferences they could simply uncheck it to be removed from that segment.
Hey there option4 - JohnP is on the money. I'm happy to add your vote for suppression lists, however at present, your best bet is to use custom fields to exclude subscribers from specific segments. Let us know if you have any questions about this :)