[CovKid66]

Did you look at that other thread I linked to? Most are actually mapping the Fn+C and Fn+V to Ctl+C and Ctl+V for copy/paste emulation instead of dedicating an entire key to the control function.

If you're dead set on remapping the mailbox key, then set up a new mapping, make sure it's set to direct key mapping, and choose the "17 control". Do an Update Config, and then soft reset for the change to take effect. I just tried it and it works fine for me that way.