Ignoring the constraint of "email client", has there been any acquisitions where the acquired product got better post-acquisition?

I can think of countless examples where it got worse, but from the top of my head, I can only think of maybe YouTube, but then only in the initial post-purchase period, and same goes for a bunch of other examples. They seem to eventually always turn sour.

Maybe GitHub? But it traded "no new features - no downtime" for "some new features - a lot of downtime" after the Microsoft purchase, so I guess it's very subjective, probably at least some people like that tradeoff.