I wish it were possible. It's been requested quite a few times. But no, we can't.

(Actually, it was possible for a while when the game was in beta, but apparently there were some technical problems with it, and SE just removed the feature rather than fixing those problems. I can see how their time constraints while trying to get the game to production-level on schedule might lead to such decisions, but I don't see why they still haven't gone back to that feature and fixed it after all this time.)