New type of addresses in Office 365 (SPO)

Few days back, a new address type suddenly appeared for all users in Office 365. The address if prefixed with the SPO string and looks like this:

I first stumbled upon this info in a thread on the Office 365 Community forums. After some digging around, I wasn’t able to find any info about this so I turned to the MVP lists. Tony Redmond’s educated guess was that the new address has something to do with the switch to using EWS for sending any SharePoint related notifications. Later on, this has been half-confirmed by Microsoft, by referring us to the following KB article. Unfortunately, this article is a bit short on details on what exactly the address is needed for, as EWS impersonation can simply work with a regular SMTP address. Maybe it’s deliberately chosen so it doesn’t interfere with the ‘regular’ SMTP addresses, as this method is also used for impersonating users without mailboxes (however that should work). In any case, details are scarce at this point, and the above article is all we have – take it or leave it 🙂

Now, here’s what we do know about the SPO addresses so far. They are automatically added to any licensed mailbox, so no shared or room mailboxes should have them. It also seems that those addresses are not added immediately upon user creation, and might appear only after the user has explicitly shared a document. The addresses do appear in the GAL, as shown in the screenshot above, and can be exposed via PowerShell just as regular SMTP addresses. For example, the following cmdlet can be used to filter out all mailboxes that do have a SPO address provisioned:

Get-Mailbox -Filter {EmailAddresses -like "SPO:*"}

The format of the address is the following: an SPO prefix, followed by an underscore and a GUID, which does not seem to correspond to the objectID in Azure AD, nor any of the other GUIDs we can expose. It does differ from user to user, so it’s perhaps some “internal” SharePoint GUID? Anyway, the last part of the address, just after the @ sign is the tenant GUID, again prefixed with SPO and underscore.

The address can be edited, removed or added just like a regular SMTP address, however for objects synced from the on-prem AD this will not be possible (although they do get the address as well!). Another interesting fact is that the address is not visible in Azure AD (via the MSOL cmdlets or the Graph API), which in turn makes it hard to confirm its existence for any non-mailbox users.

If someone does figure out more details about this, let me know please 🙂

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