I know there's a 30 day recycle bin when you delete a user's mailbox. The situation I have is this: user was originally set up with a mailbox using companyA.com as UPN and primary mailbox. Not realizing the use case for their name in another domain would require configuring it as a shared mailbox instead of an alias, the user got a secondary mailbox with companyB.com domain. After trying to delete the secondary address and creating a shared mailbox with the same name, it was obvious that the 30 day recycle bin effect was happening.
Before the knee jerk answer of "delete the mailbox and start over" - this is the president of the company and they already have mail activity in the newly migrated Office 365 environment, so we're NOT deleting the whole user.
I've found the samples online of where people delete user mailboxes from the recycle bin using PowerShell. What I'm looking for, since I'm very new at PS, is the language, if it exists, to accomplish the same thing with the secondary addresses of people who actually need that secondary address converted to a shared mailbox. I know there's a convert command for a mailbox which would convert the user's primary mailbox (not just the address), but I'm hoping to either convert the additional email address or delete the additional email address, remove it from the recycle bin immediately, and then create a shared mailbox without the 30 day waiting period.
I tried renaming the secondary once also, but I still got the error message about trying to create a shared mailbox that had a "proxy address already being used" . Any ideas how to accomplish this?