If the add-in does not work
Four symptoms, their usual causes, and what to check first.
- Last updated
- 6 minute read
- Outlook
- Troubleshooting
Almost every add-in problem is one of four things: not deployed to that person, not deployed to that device yet, a stale cache, or no signature to serve. Work through them in that order.
The add-in is not in Outlook at all
- Check the assignment in the Microsoft 365 admin centre. It is easy to deploy to a group and forget that this person is not in it.
- Give it time. Microsoft says up to 24 hours, and in practice it is usually much less.
- Ask them to close Outlook completely and reopen it, rather than just closing the window.
- On the web, a hard refresh on the Outlook tab clears most cases.
- Check the mailbox requirement. Outlook must support requirement set 1.13 or later, which rules out very old desktop builds.
The add-in is there, but no signature appears
If the Signed button is in the ribbon but nothing lands in the message, the add-in is working and Signed is not returning a signature.
| Check | Why it matters |
|---|---|
| Is the person in Users? | Signed matches on the From address. No record means no signature |
| Is their record active? | Someone disabled in Microsoft 365 is marked inactive and stops getting a signature on purpose |
| Does a design exist and is one of them the default? | With no signature to serve there is nothing to place |
| Is the From address the one on their record? | A different address, including an alias, is a different lookup |
The quickest test is Check someone's signature on the Outlook add-in page. If that renders correctly, Signed is fine and the problem is at the Outlook end.
The signature is the old version
A message keeps the signature it got when it was opened, so one that was open before your change still has the old version.
- Open a fresh message.
- Or, in the open message, choose the Signed button and then Check for changes.
- If it is still wrong after that, check the person's record: they may be matched by a different rule than you assumed.
Note: Already-sent email is never changed. A correction only affects messages written after the change.
They get someone else's signature
This is nearly always a rule matching more broadly than intended, which usually means a domain rule sitting above a department rule. See Someone has the wrong signature.
- Check the person's own record and preview their signature. The preview names the rule that chose it.
- Check the priorities on the Rules page. Highest wins, so a domain rule at a high priority will beat everything narrower.
- Check for a leftover named-person rule pointing at this person from an earlier arrangement.
What to tell us if you ask for help
- The person's email address you are testing with
- Which Outlook: web, new Windows, classic Windows, or Mac
- What you see on the deploy page when you check their signature
- Whether the Signed button is in the ribbon of a new message
- Whether it is every person or just one
With those five things we can normally tell you the cause in one reply.
Related articles
- Install the Outlook add-inOne manifest, uploaded once by a Microsoft 365 admin, and then signatures appear on their own.
- A signature is not showingWork down this list in order. It separates the four or five causes that account for almost every case.
- Someone has the wrong signatureAlmost always a rule, occasionally a cache. Here is how to tell which in under a minute.
Something here out of date, or a step that did not work? Tell us and we will fix the article. Every page is checked against the running product, so corrections are welcome.