What happens to old emails from an alias account if the main account is deleted?

What happens to old emails from an alias account if the main account is deleted?

Hi. What happens to old emails from an alias account if the main account is deleted? Is there a way to keep these old emails and set the alias account as an actual account? Please see screenshot. The account to be deleted is sean@gcmgroup.ie and the alias account to be a standalone account (not an alias) is accounts@gcmgroup.ie. Thanks in advance.