Reassigning email aliases

Reassigning email aliases

I am trying to reassign an alias from "user 1" to another email "user 2" within the group.

I deleted the alias from "user 1", then tried to add it to "user 2", but the following message pops up:

The email address is already associated with the user <user 1's email address> in your organization.

How do i successfully transfer an alias from one user to another?