We use our first names, but only after initial contact -- usually by e-mail. Only after we meet face-to-face do we give out last names.
What's troublesome for us is that we have a dedicated "adult play" e-mail address, at the big G. We use it only for contacting play partners or requesting party info. The trouble started a few years back when Google decided everyone had to use their real name to have an account. Nuh-uh, No way were we going to do that, so we picked a fake name. Google no longer requires a 'real name' (anonymity helps people escape domestic violence -- and that's a fantastic reason to be anonymous), but we can't figure out how to remove the fake name.
The upshot: Neither of us are named "Benny Vandergast". And it's not even an alias.
The fake name? "Benny Vandergast". Go look it up; Kermit and Miss Piggy would be pleased you did.
So when we write "Hey! We're J--- and J----, nice to meet you!", but the e-mail reads "From: Benny Vandergast", it's always a problem. We're trying to mitigate the issue by putting the "That's not our real name" disclaimer in e-mails and taglines,