Exchange Online PowerShell Error

Hi @Johnny Blaze

Thank you for posting your question in the Q&A Forum. 

I understand you’re experiencing an issue with mailbox permissions. Based on my research, this error can occur if the -Identity parameter is empty or not receiving a valid mailbox identifier. The -Identity parameter is required and typically expects a mailbox, such as an email address, alias, or distinguished name. 

To help resolve this, you might want to make sure that the -Identity parameter is provided with a valid mailbox value and that empty or null values are avoided.

For example, if this command is run in a script or loop, check that the variable holding the mailbox identity contains a valid string before calling the cmdlet: 

Add-MailboxPermission -Identity "******@yourdomain.com" -User "******@yourdomain.com" -AccessRights FullAccess 

Providing a valid mailbox identifier in this way usually allows the cmdlet to run without the parameter transformation error. 

You can find more details here: Manage permissions for recipients in Exchange Online | Microsoft Learn 

I hope this information is helpful. If you continue to experience issues, please don’t hesitate to share the exact command you are using so that we can assist you further. 

If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".  

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