OS won't allow me to restore from Time Machine

[Whackintosh]

This is rather odd. I'm trying to restore Mail from a Time Machine backup as something weird happened in the past week that's causing a bunch of annoying glitches (for example, while I'm in the middle of composing a message, the window will sometimes close and a new one will open up, mid-typing).

I figured the easiest thing to do would be to do a restore from a Time Machine backup, but I'm getting the following message: "Mail” can’t be modified or deleted because it’s required by macOS."

Is there something I'm doing incorrectly?

 

[Matthew Jones]

That seems to be a rather old issue. Here is a discussion that might help you: https://discussions.apple.com/thread/3668441