Bug moving primary email address on a mail account

We had an important employee leave - lets call him John Smith - with the well known email address - lets call it johnsmith@example.com. I wanted to keep the account for now as a easily accessible archive but move the email address johnsmith@example.com as an alias for another account. So I created a new alias johnsmith@backend.example.com, set that as the mailbox address, and deleted the alias johnsmith@example.com.

I then went to the other account to add the alias but got the error: "email alias already exists."

After some troubleshooting it seems that you can not delete an alias that is set as the "primary email address" on the Security -> Login email address page. Once I changed the primary there to johnsmith@backend.example.com I was able to delete the alias and add it to another account.

In a possibly related bug if I delete an alias, then go to the Security -> login email address page, the recently deleted email address will still show. Once the page is refreshed it goes away.

The Login email address page and the alias page have related data but are treated as if they are unrelated by the user interface. Changing the data on either page needs to update the other page, or even better the data should all be managed from the same page. However, it should NOT confirm that an alias is deleted if the alias is not deleted!

Zoho customer service does not seem to comprehend the problem. Hopefully someone at Zoho will read about it here and it will be fixed in an upcoming update :)