Changing email account names

I’m very new to Nextcloud and have searched high and low and cannot seem to find my answer. I simply want to rename my email accounts. For example, from “blahblah@blahblahblahblahblah.com” to “BL | BL.com” Surely, there’s a way to do this, right?

» Screenshot of what I’m trying to do «

I am running NC version 25.0.1.

Anyone? hearing crickets