Microsoft’s Cloud Email Signatures Solve a Problem for Outlook

Email Signatures Shared between Outlook and OWA But Not a Panacea for Signature Management

A reader pointed me to Microsoft’s Email Signature Gallery and asked if these signatures could be used with Outlook and OWA. The answer is yes, and there’s documentation to show how, which is always nice.

The gallery of email signatures is in a Word document (Figure 1), which can be downloaded or edited online. Editing is important as you need to update one of the sample signatures to use it.

Microsoft's Email Signatures Galler
Figure 1: Microsoft’s Email Signatures Gallery

After making the appropriate changes, you can cut and paste the signature into OWA or Outlook desktop (Figure 2) and the wonders of roaming signatures will make it available in both clients. Basically, all you need to do is replace the photo, update the values for title, phone numbers, organization, and address, and add links for your web site and Twitter handle. The email signatures gallery sounds like a very useful tool, but some downsides exist.

Adding an email signature from the gallery to Outlook desktop
Figure 2: Adding an email signature from the gallery to Outlook desktop

According to message center notification MC340845 (October 27, 2022), rollout of roaming signatures should now be complete. Microsoft also refers to the feature as “cloud signatures.” Both mean the same thing. The signature information is in user mailboxes and clients download signature information from the mailbox to apply signatures to messages.

Set-MailboxMessageConfiguration Remains Broken

The first issue is that Microsoft hasn’t addressed the issue with roaming signatures that broke the Set-MailboxMessageConfiguration cmdlet by removing HTML support for signatures in OWA. Microsoft removed the warning from the documentation that roaming signatures causes the problem, which was nice of them. The problem means that if you’ve taken the time to develop nicely-formatted signatures for OWA, any scripts that apply OWA signatures to mailboxes won’t work.

You can’t make an omelette without breaking eggs and Microsoft would say that you can’t introduce roaming signatures and give users a choice of signatures to use without breaking something. At least, I think they’d say this because they broke something.

It’s reasonable to assume that an update would be necessary for the Set-MailboxMessageConfiguration cmdlet after the introduction of roaming signatures. The update needs to:

  • Support the storage of signature information in the user’s mailbox.
  • Support reading and setting of multiple signatures per mailbox.
  • Support selecting a default signature for new messages and replies from the available set.

It would be nice if Microsoft fixed the cmdlet problem so that those who’ve invested time and energy to develop PowerShell scripts to manage email signatures can continue to benefit from their work.

Roaming Signature Data in User Mailboxes

Up to now, the cmdlet could retrieve signature information from its settings. Now it must read data from the ApplicationDateRoot\49499048-0129-47f5-b95e-f9d315b861a folder in the non-IPM part of the mailbox. The MFCMAPI utility reveals that each signature has its own sub-folder (Figure 3) along with other information stored in ApplicationDateRoot\49499048-0129-47f5-b95e-f9d315b861.

MFMAPI reveals where email signatures are stored in user mailboxes
Figure 3: MFMAPI reveals where email signatures are stored in user mailboxes

The folder for a signature has a contents table storing some message items. The message items hold the signature data (Figure 4) in HTML format, including graphic elements like icons.

How email signature information is stored in the mailbox
Figure 4: How email signature information is stored in the mailbox

It’s obvious that the implementation of roaming signatures is very different in many ways to the simplicity of the earlier approach taken by OWA, which only supports a single HTML signature.

Roaming Signatures Work for OWA

In any case, signatures updated in Outlook desktop become available to OWA (and vice versa) after a period for the clients to learn about updates and refresh caches. Figure 5 shows the signature from the email signatures gallery that I pasted into Outlook as it appears in an OWA message.

A roaming signature entered in Outlook desktop turns up in OWA
Figure 5: A roaming signature entered in Outlook desktop turns up in OWA

Current State of Play

The current state of play is therefore that clients that support roaming signatures (OWA, the Monarch client, and the latest Outlook click to run builds) share signatures stored in user mailboxes. No matter what client someone updates a signature in or the source of the signature (from the gallery, from another user, or generated by the user), the clients will all pick up and use that signature.

Does this mean that ISV signature management products like Code Two’s Email Signatures for Office 365 are out of business? Not at all. Roaming signatures fix a problem in that a common signature is now available within the Outlook client family. It’s not a universal panacea for email signature management and does nothing about making sure that people use suitable corporate signatures throughout the organization, including with non-Outlook clients. If you’re interested in central management of email signatures across multiple clients, there’s still a ton of value to be gained from investing in the right tools.


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5 Replies to “Microsoft’s Cloud Email Signatures Solve a Problem for Outlook”

  1. Do we know how well this works from the Mac Outlook client? i.e. formatting issues? Nice that you mention the CodeTwo signature solution – we have been using this solution for years to provide unified email signatures, customized by office location and we are happy with the solution. The one feature we have not implemented is custom fields. We would like to include individual LinkedIn and Twitter links but the only built-in option that is easy to manage has been to use the Fax number (!!) field.

    1. I don’t have a Mac to try the signatures out on. Maybe someone else can help. But before this can happen, the Outlook for Mac client needs to support roaming signatures. I don’t think that has happened yet.

  2. Thanks for this article – really informative.

    In my Message Center, the message you referred to is listed as MC450845. Not sure if there is a difference depending on tenant type or if that was a typo in the article.

    I’ve reached out to Microsoft to confirm what I suspect – that this feature won’t work for those of us with Office 2021 LTSC. It would be nice if that LTSC limitation was mentioned more consistently in new feature documentation.

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