What the API covers
Ten modules, and the two ways signatures actually reach a message.
- Last updated
- 5 minute read
- API
The API mirrors the portal. Anything you can do by clicking, you can do by calling, with the same plan rules and the same audit trail.
The modules
| Module | What it does |
|---|---|
| Overview | The index and the OpenAPI specification. No key needed for either |
| Organisation | Your details, the company defaults used in signatures, and usage counts |
| Signature templates | Create, edit and assign the designs your organisation uses |
| People | Create, update and import the people signatures are built for |
| Departments | The department list used to scope rules and campaigns |
| Assignment rules | Decide which template applies to which people |
| Campaigns | Dated banners appended under signatures |
| Signature delivery | Look up a signature for an address, or stamp one into a body |
| Audit log | A paged, read-only history of everything that changed |
| API keys | Create, limit, rotate and revoke the keys themselves |
The two ways signatures reach a message
Most integrations want one of these, and picking the right one early saves rewriting later.
| Outlook add-in | Stamp endpoint | |
|---|---|---|
| Where it runs | Inside Outlook, where the person is writing | On your mail relay, gateway or flow rule |
| Who it suits | Microsoft 365, in Outlook on the web, Windows and Mac | Any mail system, including non-Microsoft |
| Setup | Upload a manifest once as an admin | Call the API from the relay |
| Idempotent | Places the signature once per message | Returns the body untouched if it is already stamped |
| Needs a person signed in | Yes, naturally | No |
Note: A lookup (GET /signature?email=) returns a person's finished signature without touching a message. It is the one to use for intranets, onboarding emails and anything that needs to show someone their signature.
API or portal?
- Use the portal for design work, one-off changes and anything you want to look at. It is faster and there is nothing to get wrong.
- Use the API for anything repeatable: syncing people from a system that is not Microsoft 365, pushing signatures into a mail relay, or keeping an intranet in step.
- Use the API when a change needs to be part of a deployment, a review process or a runbook.
Tip: The portal keeps working whatever the API does. If you build a nightly import and it breaks, you can still fix someone's job title by hand from the user list.
Related articles
- Make your first API requestThree requests that prove the key works, plus what every error response means.
- Create and manage API keysOne key per system, the narrowest scopes that work, and a rotation plan you have actually written down.
- Install the Outlook add-inOne manifest, uploaded once by a Microsoft 365 admin, and then signatures appear on their own.
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.