Why Microsoft’s Slowness in Delivering Outlook Roaming Signatures Affects OWA

Scripts Stop Working without Warning

In 2020, I wrote about how to create and apply corporate email signatures for use by OWA. Recently, things started go wrong and some people reported that the code didn’t work any longer. The issue is linked to the work Microsoft is doing to deliver Outlook roaming signatures, a much-anticipated feature that’s currently delayed until October 2022. The good news is that some progress is visible. The bad is that the development has caused problems for tenants that could have been avoided.

The Broken Set-MailboxMessageConfiguration Cmdlet

I’m all for Outlook roaming signatures. It’s a nice feature that should have existed across the entire Outlook family long before now. One of the consequences of the move is that Microsoft deployed code to allow OWA (and the Monarch client) to support multiple signatures (Figure 1) instead of the previous situation where OWA supported just the one. The code is available in all tenants, except those who have asked for it to be removed (see below).

OWA support for multiple signatures

Outlook roaming signatures
Figure 1: OWA support for multiple signatures

Outlook desktop has long supported multiple signatures, so getting the functionality in OWA is goodness. However, the change means that the SignatureHTML parameter of the Set-MailboxMessageConfiguration cmdlet now includes a warning that:

This parameter doesn’t work if the Outlook roaming signatures feature is enabled in your organization. Currently, the only way to make this parameter work again is to open a support ticket and ask to have Outlook roaming signatures disabled in your organization.

In other words, the scripts developed to create nicely-formatted HTML signatures for OWA won’t work. Existing signatures remain in place and will work, but the cmdlet might fail if you try to update a signature. Note the word “might.” The strange thing is that sometimes the cmdlet fails and sometimes it works. For instance, I just ran these commands to set and check a HTML signature for a mailbox, and everything worked:

Set-MailboxMessageConfiguration -Identity $M.UserPrincipalName -SignatureHTML $SignatureHTML -AutoAddSignature $True -AutoAddSignatureOnReply $False

Get-MailboxMessageConfiguration -id Terry.Hegarty | Format-List SignatureHTML


SignatureHtml             : <html>
                            <body>
                            <b>Terry Hegarty </b>Valued Employee<br>
                            <b>Office 365 for IT Pros</b> Terenure, Dublin, D18A42Z2 Ireland<br>
                            / Email: <a href="mailto:&quot;Terry.Hegarty@office365itpros.com&quot;">Terry.Hegarty@off
                            ice365itpros.com</a><br>
                            <br>
                            </body>

But I know that many other people have difficulties making the cmdlet work, so the behavior is inconsistent and unpredictable, which is just the kind of unhappy behavior no one likes in code.

The only bright spot on the horizon is that the beta channel builds of Outlook for Windows share the same signature information with OWA and the Monarch client (Figure 2). Outlook for Windows now reads the signature information from a hidden folder in user mailboxes instead of the system registry. The folder for signature information is ApplicationDateRoot\49499048-0129-47f5-b95e-f9d315b861a6, with a separate sub-folder used for each signature. An item inside the folder holds the signature text. It seems like roaming signatures are getting closer, even if their development has caused some upheaval.

Outlook for Windows supports roaming signatures
Figure 2: Outlook for Windows supports roaming signatures

Only One Fix (or Patience Required)

As those involved in tenant management know, living with change is a constant inside Microsoft 365. In this case, change is happening (slowly) to enable a good outcome (Outlook roaming signatures), but Microsoft overlooked the need to upgrade the Set-MailboxMessageConfiguration cmdlet (or an equivalent Graph API) to allow organizations to continue managing signatures for mailboxes. That’s more than regrettable, especially when it happened with a total lack of communication to tell customers what’s happening.

If you run into the problem, Microsoft suggests that you open a case with Microsoft Support to ask them to arrange for the roaming/multiple signatures feature to be removed from the tenant. This process is likely to take a few days to complete. The alternative is to ignore the issue and wait until Microsoft delivers Outlook roaming signatures as promised in October. That update might, or might not, happen on schedule. But that’s the way of the cloud…


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