Outlook signature not syncing to Outlook on the web? Fix it

Microsoft stores classic Outlook signatures on the device where you made them, and says to create a signature in both products. If a signature you made in desktop Outlook disappears after a while, Microsoft has a known issue for that, marked fixed in November 2024. Check your build, then apply its workaround.

Why does my signature show in desktop Outlook but not on the web?

Desktop Outlook and Outlook on the web keep separate signature lists. Microsoft's signature article says that if you use one Microsoft account in both, you need to create the signature in each product.

Roaming signatures are a separate feature, and they cover less than most people expect. Outlook for Windows build 2303 or higher can roam signatures across devices, on a Microsoft 365 or Outlook.com mailbox. Microsoft copies the default signatures for new messages and for replies and forwards to the mailbox. Other signatures stay on the device under "Signatures on this device", and you cannot edit them unless they are linked to an account. Microsoft's roaming page does not describe sync to Outlook on the web or Outlook for Mac.

Which Outlook build do I have?

In classic Outlook for Windows, select File, then Office Account. If you do not see it, choose Help. The version and build appear under Product Information. In new Outlook, select the Settings gear, then General, then About Outlook.

Microsoft's known-issue article lists a fixed build for each channel. Current Channel received Version 2410 (Build 18129.20124). Beta and Current Channel Preview received Version 2411 (Build 18205.15010). Production channels received the fix in the November 12, 2024 public update. If your build is older than the fix for your channel, update Office before you try anything else.

How do I stop a signature from disappearing in desktop Outlook?

Microsoft says account data was cached incorrectly in a registry value, so a new signature could be uploaded incorrectly and then deleted. The fix did not repair accounts that were already affected. Microsoft's workaround renames one registry key. Export the key first, because this is a registry change.

1. Close Outlook completely.
2. Open Registry Editor (regedit).
3. Go to HKEY_CURRENT_USER\Software\Microsoft\Office\Outlook\Settings.
4. Right-click the Settings key and choose Export. Keep the .reg file.
5. Right-click the Settings key again, choose Rename, and type Settings_old.
6. Start Outlook.
7. Check your signatures in desktop Outlook, then in Outlook on the web.

Microsoft's article does not say what else the Settings key holds. Check your Outlook settings after the restart. If something you need is missing, import the .reg file to put the key back.

What if the signature still disappears?

Check for tools that edit signature files or the registry. Microsoft says third-party add-ins that edit signature files or the registry will not work when roaming signatures are enabled. If a script or deployment tool does this, test it with one user before you roll it out.

An admin who needs roaming turned off on a machine can set the DWORD DisableRoamingSignatures to 1 at HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Setup. Group Policy uses HKEY_CURRENT_USER\SOFTWARE\Policies\Microsoft\Office\16.0\Outlook\Setup. This stops roaming on that machine, so the signature no longer follows the user to other devices.

If the signature will not save on the web at all, read Outlook on the web signature not saving first. It covers the web-side checks, including the PowerShell case.

How do I keep the same signature in both?

Keep one master copy of the signature HTML, and paste it into each editor. Desktop Outlook, Outlook on the web and new Outlook each have their own editor, so send yourself a test from each product rather than trusting one preview. If you build the signature in the email signature generator, keep the output so you can paste the same version again.

Sources

• Microsoft Support, "Signatures are not syncing between Outlook Desktop and Outlook Web App" (known issue, last updated November 6, 2024): https://support.microsoft.com/en-us/support/known-issues/signatures-are-not-syncing-between-outlook-desktop-and-outlook-web-app
• Microsoft Support, "Outlook roaming signatures": https://support.microsoft.com/en-us/office/outlook-roaming-signatures-420c2995-1f57-4291-9004-8f6f97c54d15
• Microsoft Support, "How to add and change an email signature in Outlook": https://support.microsoft.com/en-us/outlook/mail/how-to-add-and-change-an-email-signature-in-outlook
• Microsoft Support, "What version of Outlook do I have?": https://support.microsoft.com/topic/b3a9568c-edb5-42b9-9825-d48d82b2257c