I recently had a problem in which Microsoft uniquely and quite unreasonably banned the upstream provider of my ISP from emailing their users. There's no allegation that I'm responsible for this, but I'm stuck with it until it gets worked out.
I was just trying to figure out a way to segment the Microsoft domains off into a separate list, and hopefully send to all confirmed subscribers not on that list, but I don't see any easy way of doing this. If I'm interpreting my interface correctly, I'd have to search subscribers, open each profile and edit.
This would be quite a prohibitively labor intensive chore in my mailing list.
If there's a way to do it, I'll be interested to know. If not, I offer this as a feature suggestion.