Install the Outlook add-in
One manifest, uploaded once by a Microsoft 365 admin, and then signatures appear on their own.
- Last updated
- 6 minute read
- Outlook
- Setup
The add-in is what puts signatures into Outlook. It is installed once for the whole organisation from a manifest that Signed generates for you, filled in with your own details.
Before you start
- At least one signature is designed and saved
- People exist in Users, or a Microsoft 365 sync is connected
- You have access to the Microsoft 365 admin centre
- You know who the add-in should be assigned to: everyone, or a pilot group first
Note: The add-in only runs automatically when an administrator deploys it. If someone installs it themselves from AppSource, the automatic signature handling stays switched off, which is why the admin route is the one to use.
Deploying it
Outlook add-in
Get signatures into Outlook for everyone in your organisation.
Set-up progress
- Download your manifestIt already carries your organisation's details.
- Add it to Microsoft 365An admin uploads it in the Microsoft 365 admin centre.
- 3Wait for it to reach peopleUsually under 24 hours.
Add-in status
Last checked 2 minutes ago
Client key
clt_9f2c••••••••
Already in your manifest. You only need it for other mail integrations.
Step 1 of 4
Download the manifest
Signed builds it for your organisation, with your name, logo and client key already in place. There is nothing to fill in by hand.
Reduced motion is on, so the tour waits for you. Use the arrows or the list to move through the steps.
Rolling out to a pilot group first
For anything above a couple of dozen people, assign the add-in to a pilot group first. It costs nothing and it turns the rollout into a non-event.
- Upload the manifest and assign it to a security group of five or six people who will report back on what they see.
- Ask them to write a new message, reply to one, and forward one.
- Ask one of them to change the From address and confirm the signature swaps.
- Once you are happy, edit the assignment to include everyone.
Tip: Include someone with an unusual setup in the pilot: a Mac, an older Windows machine, someone who works mostly from their phone. Those are the people who find the problems.
What the add-in actually does
The add-in listens for two moments in Outlook and nothing else:
| When | What happens |
|---|---|
| A new message is opened | The signature for that person is fetched and placed in the message |
| The From address is changed | The signature is fetched again and swapped for the one that matches the new address |
It also adds a Signed button to the ribbon of a message you are writing. It opens a small pane that shows the signature, with buttons to insert it again or check for changes.
Your manifest.xml
Each organisation downloads its own copy, filled in with its name, logo and client key.
<OfficeApp xsi:type="MailApp">
<Id>7f3c…</Id>
<DisplayName DefaultValue="Halden & Rowe signatures"/>
<Description DefaultValue="Adds your email signature"/>
<Version>1.0.0</Version>
<Hosts><Host Name="Mailbox"/></Hosts>
<Requirements>
<Set DefaultMinVersion="1.13" Name="Mailbox"/>
</Requirements>
<FormSettings>…</FormSettings>
</OfficeApp>Where to add it
- 1. Microsoft 365 admin centre
- 2. Settings, then Integrated apps
- 3. Upload custom apps
- 4. Choose Outlook, then assign
People with the add-in
118 / 142
Takes up to 24 hours to reach everyone.
- It needs Outlook on the web, new or classic Outlook for Windows, or Outlook for Mac, with mailbox requirement set 1.13 or later.
- It asks Signed for the signature every time a message is opened, and keeps a saved copy in case Signed can't be reached.
- It knows whether the message is a reply and whether anyone outside your organisation is on it, and updates the signature as people are added. The recipients' addresses are never sent to Signed.
- It never sends anything. It only places HTML into the message the person is already writing.
Other mail clients
Outlook on mobile has no support for this kind of add-in. People who mostly work from a phone should keep a copy of their signature in their phone's own signature settings, or the team can use the API to push signatures into another system.
For anything else, your client key and the API let another system ask Signed for the same signature the add-in would place.
Common questions
Do people need to install anything themselves?
No. Once the admin assigns the add-in, it appears for them automatically, usually within 24 hours.
Will it overwrite a signature someone typed themselves?
The add-in places its signature in the message body. If someone has written their own signature by hand, the standard advice is to leave them to it; the add-in does not remove anything a person has typed.
Can I remove the add-in later?
Yes. Remove it in the Microsoft 365 admin centre and signatures stop being added. Nothing in Signed is deleted.
Related articles
- What people see in OutlookA new message, a reply, a forward and a From swap: the four cases people ask about.
- If the add-in does not workFour symptoms, their usual causes, and what to check first.
- Check what people will seePreview one person's finished signature, including banners and disclaimers, without sending a test email.
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