I have been able to simply tell people in ebay messages xxxxx at g mail and it goes within a conversation; without problems.. they didn't have great filters. Maybe it's harder now; but you can always ask for contact info to be shipped with the item; and usually there is a return address on the package.
The big issue is to able to conduct sales outside of ebay in the future with someone you meet on the platform and I don't think they will ever be able to control that!
The worst thing they can do is take away your right to use the platform; which happened to me and I told them I'd be moving to AMZ, and I could tell the guy didn't like being told that.. I guess they had not considered that part yet ;-)