That's us, with our workplace xxx's and ooo's. I know that especially as "the boss," you're not supposed to do that. At least I think that's what Wharton or wherever would say. (I know they teach more important stuff than this. Just playing.)
I used to be more proper and sign my business letters "Best always." Now it's "Take care," or in the case of these guys (note our constant contact even over weekends -- jeez) xoxooxoxoxoxoxxxxxooxo. How do you sign off on your official stuff? And would it bug you if your boss wrote "xo" to you? Xo!