said by Hall:
You sure ? I trashed "Mail" a long time ago with no ill-effects. I think there was (1) update out of 3-4 maybe that put it back.
Let's say, instead of trashing it, that you put it somewhere else...
... and then OS X 10.8.3 comes along and installs a new mail.app (that's assuming you use the "full" instead of "delta" update. If it's the Delta update, it's even worse.)
Now you'd have two Mail.apps.... which one gets launched when you click on a mail message or a mailto: link in your browser? Now you're using, say, a 10.8.0 Mail.app which is expecting certain versions of libraries that were replaced in 10.8.3.
Just an example.
... if you use Delta updates, it's even worse. You might end up with bits n pieces of things.
Just a bad idea overall ....