Signature Management is Complex
Companies often want to impose corporate branding and a common style to the email signatures applied by email clients to outbound messages. Managing signatures and making sure that the right signature is applied can be complicated, which is why so many companies like CodeTwo Software, Crossware, and Exclaimer develop and sell email signature management software.
The difficulties of dealing with Outlook for Windows signatures is described in a post explaining how to build and apply a HTML signature with PowerShell. Updating the system registry is often complicated and Outlook doesn’t make it easy. By comparison, updating the signatures used by OWA with PowerShell is more straightforward.
Roaming Signatures for Outlook Click to Run
One of the reasons why Outlook signatures cause management challenges is the need to update signatures on individual PCs. Microsoft is about to make things easier by introducing roaming signatures for Outlook. In other words, you can create a signature on a PC and that signature will be available on any PC you sign into. For now, the feature won’t work for Outlook for Mac and OWA will continue to use its own signatures, but you couldn’t rule out a plan that would see the same roaming signatures being used across all Outlook clients.
To make this arrangement work, the signature information is stored in Exchange Online user mailboxes and retrieved by the click-to-run version of Outlook (part of the Microsoft 365 enterprise desktop apps). In other words, the feature isn’t available on-premises because Exchange Server doesn’t store signatures in its mailboxes. Outlook 2016 and Outlook 2019 will continue to use the system registry to store signature settings (the RTF files containing the signatures are in the file system).
Signatures that aren’t associated with an Office 365 account won’t roam because they can’t be matched with an Exchange Online mailbox. These signatures, which might belong to people who use Outlook with non-Exchange servers, remain in place and available.
Synchronizing Signatures to Exchange Online
According to Microsoft 365 roadmap item 60371, Microsoft expects that roaming signatures will be available in June 2020. If all goes well, the June 2020 update for Outlook (monthly channel) will be the first version to support roaming signatures. After you install the update, Outlook will read existing signature information from the system registry and write it into the mailbox. The current setup of signature information in the system registry and signature files on disk remains to support offline working. Outlook on other PCs will pick up the updated signature the next time the user signs in.
Microsoft says that third-party add-ins will have to disable roaming signatures to continue to work. In the future, Microsoft expects to deliver an API to allow add-ins to work with roaming signatures.
Outlook doesn’t block users from updating signatures through its Options (Figure 1). Subsequent changes to the signature made in Outlook will be synchronized with Exchange Online. Each time Outlook starts, the client checks if the signature in the mailbox is newer than its copy and downloads the information if needed.
Disabling Roaming Signatures
It’s possible that an organization doesn’t want Outlook to use roaming signatures. In this scenario, you can disable the feature by updating this DWORD value in the registry:
Set the value to 1 to disable roaming signatures. If the value doesn’t exist or is set to 0, Outlook uses roaming signatures. Microsoft views the registry value as a holding measure until they do the work to allow third-party add-ins to interact more gracefully with roaming signatures. When that API is delivered, you can expect Microsoft to deprecate this setting.
Roaming signatures is a welcome update that people have wanted for a very long time. I doubt that the advent of the feature will affect the ISV market for email signature management products because the process of making sure that the right signature is used by the right person is more complicated than copying signatures between PCs. Corporate branding matters!
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