Microsoft has started to roll out a change to the way email signatures work.
If you are impacted, you have two options:
Implement an interim solution proposed by Microsoft
If you opt for the interim solution offered by Microsoft, here are the steps to follow:
Manually disable the Outlook roaming signatures feature.
To manually disable the Outlook roaming signatures feature:
1️⃣ Launch the RegEdit
Launch the RegEdit (Registry Editor).
2️⃣ Browse to:
3️⃣ Select DWORD (32-bit) Value
Right-click anywhere on the right panel, select New then select DWORD (32-bit) Value.
4️⃣ Enter the DWORD name a:
Enter the DWORD name as DisableRoamingSignaturesTemporaryToggle and press [Enter].
5️⃣ To edit the value, you can:
Either right-click the DisableRoamingSignaturesTemporaryToggle and select Modify
Or double-click DisableRoamingSignaturesTemporaryToggle.
The Edit DWORD (32-bit) Value window is displayed:
In Value data, enter the value 1.
6️⃣ Save the changes
Click OK to save the changes and close the window.
7️⃣ Restart Outlook
Restart Outlook for the change to take effect.
8️⃣ Alternative REGEDIT path
If this still doesn't work, you need to access this path (or create it) and then create the DisableRoamingSignaturesTemporaryToggle key: