Applies to: Microsoft 365: Outlook for Windows, Mac, web, iPhone and Android
The BulkSignature add-in adds the latest signature to each new message in Outlook.
How the add-in adds a signature
For every new message, the add-in asks for the latest signature. If that takes too long, it inserts a saved copy instead, so the message isn't held up.
Slow sign-in: In Outlook for Windows, Outlook for Mac and Outlook on the web, the add-in waits for background sign-in to finish. If sign-in can't succeed, it inserts the saved copy.
Weak connection: The add-in waits a few seconds for the latest signature. Then it inserts the saved copy, so the employee can edit the message right away.
How long the add-in waits before using the saved copy:
iPhone and Android: about 5 seconds
Windows, Mac and web: about 8 seconds
The saved copy is also used whenever the signature can't be prepared.
About the saved copy
One per mailbox: The add-in keeps a saved copy for the employee's main mailbox and for up to three other mailboxes they send from, such as an alias or a shared mailbox. Each copy is used only for its own mailbox.
Created on a good connection: A saved copy exists only after the employee has written a message from that mailbox on a good connection. In classic Outlook for Windows, this has to happen again after the September 2026 update. Until then, no signature is inserted on a slow connection.
May be out of date: If you've recently changed the signature, the saved copy may still have the previous version.
If a new message has no signature
Open the BulkSignature task pane on the message.
If a bar says Automatic signature didn't run for this message, select Insert signature. The right signature is added to the message.
In Outlook for Mac, quit and reopen Outlook (⌘Q) so automatic insertion works again for new messages. Closing the Outlook window isn't enough.
The bar appears in Outlook for Mac, Outlook for Windows and Outlook on the web.
The bar appears on a message that already has its signature? This can occasionally happen in Outlook for Mac, new Outlook for Windows and Outlook on the web. Select Dismiss for this message.
Known limitations
Outlook for Mac: On some Macs, automatic insertion can stop without warning until Outlook is quit and reopened. The task pane bar shows when this has happened and lets the employee add the signature, but the underlying issue isn't fixed yet.
No connection: Outlook doesn't start add-ins when it's offline, so no signature is inserted, not even the saved copy.
Very weak connection: The wait starts only once Outlook has started the add-in. On a very weak connection, Outlook itself can take longer to do that.