Finding Existing Plus Addresses

Exchange Online will automatically enable “Plus Addressing” for all tenants from Jan 2022. This change may cause issues if you have existing mailboxes where the SMTP address contains a + sign.

That is, directors+managers@contoso.com would be considered a broken email address from Jan 2022 in Exchange Online.

So you need to check you have no “Plus Addresses” and the way to do this is in Exchange Online PowerShell. Run the following cmdlet and it will return all the mailboxes, contacts, groups etc. that contain a “+” in the address. You need to update these recipients to remove the address that contains the “plus”.

Get-Recipient -ResultSize Unlimited | where {$_.EmailAddresses -ilike "*+*"} | FL Name,DisplayName,OrganizationalUnit,EmailAddresses