Work email disappears when changing employer. Also I strongly don't want the 'hi Jon, want to work here instead?' messages going through corporate IT.

One CEO I know sent a company wide email with a subject line "Explanation???" and a body consisting of a screenshot of an employee's LinkedIn profile where it stated that he was open for work.

I thought blasting it was a mistake, but it wasn't. The employee, upon seeing that, quit on the spot. The CEO tried to convince him to stay and have a conversation, and the employee didn't want to hear anything after that.

I think he even just forgot to update that thing, but that paranoia and lack of tact and class pushed him to actually look for work elsewhere.

My professional identity transcends whatever client/employer I happen to be working with right now.

So for me, absolutely.

I think so. I mean I can definitely imagine situations where it's preferable to network with a work email especially when working in an early stage startup. But at a regular Software Engineering job I'd probably go with my personal email