User terminology

Under Manage Users I only have one User named xysada

Under Manage Mailboxes it says User in the first colum. According to this I have 3 Users named Contact. This is causing confusion.

Under Manage Mailboxes Destination is actually the User and User is the Email address prefix. To solve this issue you should replace User and Domain with Email address and replace Destination with User

Destination can also be forwarded to a remote email address, so “User” wouldn’t work. Per RFC 2821 § 2.3.10 the “User” field as presented is called “local-part” but the term is broadened to include “user names”, so that’s how we use “User” instead of “Local-part”.

To note: it’s a distinction of “username” versus “user”.