I run MSE (the x86 Vista/7 install) on Windows Server 2003. It works quite well, though I do realize that it's not officially supported.
However, the last updates show the same "support ending" message that showed up on Windows XP last year. Now, I guess I'm surprised that the code in the Vista/7 installer would detect Server 2003 as XP, but moreover, I'm surprised that this installer would even have the end of support message. My hope was that since MSE in not even supposed to recognize Server 2003, that it would just keep running without issue until January 2020. After all, I used the installation file for Windows Vista and 7.
So I went back to v4.304.4 (I think that's right...lol). It takes current definition updates, and keeps running with the notice. I wondered if any one might've know another way around this perhaps.