What Sigil is
Sigil is an email signature platform for organisations running Microsoft 365. An administrator designs one or more signature templates in a web portal. Every person’s signature is then rendered from those templates, personalised from the company directory, and applied inside Outlook as they compose a message.
It is built by Tophhie Cloud and delivered as two pieces: a web admin portal at
portal.usesigil.app, and an Outlook add-in served from static.usesigil.app
that a Microsoft 365 administrator deploys once across the organisation.
| Category | Email signature management |
| Platform | Microsoft 365 and Exchange Online |
| Delivery | Outlook add-in plus a web admin portal |
| Identity | Microsoft Entra ID, with no separate login |
| Price | £0.70 per licensed mailbox per month, 14 day free trial |
| Vendor | Tophhie Cloud |
The problem it solves
Section titled “The problem it solves”Left to individuals, signatures drift. Fonts wander, job titles go stale, disclaimers get dropped, images break. Marketing wants brand consistency and the occasional campaign banner. Legal wants a disclaimer that nobody can forget. IT owns the deployment and would rather not touch a thousand mailboxes to change a phone number.
Sigil moves all of that to one place. Templates are authored once, personalised per person from Entra and Microsoft Graph, applied automatically by the add-in, and changed without redeploying anything.
It also measures itself. Client-side signature tools are usually blind to their own success, because nothing reports back. Sigil records both the signature requests it serves and the outcome of each attempt to apply one, so the portal can tell you which mailboxes are covered and which have never had a signature applied at all.
Who it is for
Section titled “Who it is for”Sigil fits organisations on Microsoft 365 with Exchange Online, because the add-in and the directory reads are both Microsoft-native. Typical buyers are IT and Microsoft 365 administrators, often replacing Exclaimer Cloud, CodeTwo or a manual process.
| Who | What they get |
|---|---|
| IT and M365 admins | Admin-consent onboarding, one manifest to deploy, Entra-native auth, adoption telemetry |
| Marketing | A drag-and-drop designer, org-wide templates, time-boxed banners, tracked links |
| Legal and compliance | Footers appended at render time, per email domain, that no template can omit |
| Everyone else | A correct signature with no effort, and an optional pane to apply it by hand |
Organisations not on Microsoft 365, such as those on Google Workspace, are not a fit today. The product is built on Outlook add-ins and Entra.
What it does
Section titled “What it does”The feature set divides roughly into authoring, targeting, and monitoring.
Authoring covers the template library, a drag-and-drop designer, a direct HTML editor, drafts and publishing with a line diff before you go live, version history and rollback, and import and export as portable JSON.
A designed signature can also carry images that differ for each sender: a QR code holding that person’s own contact card, and their Microsoft 365 profile photo. See per-user images. The same contact card is available as a download link for recipients reading on a desktop, where a QR code is no use.
A publish can also be staged, going to 10% of mailboxes and spreading only as the add-in reports that the new version is applying. Because Sigil measures whether a signature was applied rather than only served, a rollout that starts failing more often than the version it would replace withdraws itself.
It can equally be booked for a future instant, for a rebrand that has to land at a particular moment, or put behind an approval step so that only an admin can put a body in front of users.
Where the directory is the wrong home for something, profile fields fill the gap. An organisation defines custom fields such as pronouns or a personal booking link, and colleagues fill in their own at a page of their own. Nothing there is read from or written back to Entra.
Targeting decides who gets what. Assignment rules pick a template by directory attribute or Entra group membership. Banners inject a time-boxed campaign image above or below every signature. Footers append a legal block per email domain.
Monitoring covers activity and adoption, including the list of mailboxes that have never applied a signature, attribute coverage across the directory, link click analytics with security scanner traffic filtered out of the totals, and an append-only change log of what admins did and when.
Most of that also arrives without anyone opening the portal, as a weekly health digest to the organisation’s administrators.
The same apply telemetry feeds cost management, which names the licensed mailboxes that have never used a signature so they can be taken off both the service and the bill.
Any of this can be driven from a script rather than the portal. An API key is a credential for an organisation rather than a person, scoped to the areas you choose and optionally read-only, which is what a joiner and leaver runbook or a nightly reporting pull uses.
How people experience it
Section titled “How people experience it”Most people never see Sigil. The add-in fires on new messages, replies and forwards, and on a change of sending account. There is no task pane to open and nothing to click.
A compose ribbon button called “My signature” exists as a fallback. It applies the signature on demand, explains why it did not if something failed, and offers a download of the signature as a standalone HTML file. It also completes the first-run sign-in that the silent event handler cannot do on its own. See how your signature works.
Outlook on Windows, on the web and on Mac get full support. Outlook mobile gets event-based application but no manual pane, because Outlook mobile activates add-ins in read mode only.
What it does not do
Section titled “What it does not do”Some limits are worth knowing before you commit.
Sigil is Microsoft 365 only. Automatic application requires administrator deployment of the add-in, because event-based add-ins do not auto-launch when a user installs them individually. Propagation after deployment takes 6 to 72 hours.
Outlook itself constrains the templates: a rendered signature must stay under 30,000 characters, SVG is not supported, and images are attached inline rather than hosted. Outlook constraints covers each one and why it exists.
On the very first compose, or after an MFA prompt or an expired session, the silent sign-in inside the event runtime can fail. The signature applies once the person opens the “My signature” pane, and it self-heals from there.
Where to go next
Section titled “Where to go next”Read how it works for the mechanism, or go straight to the quickstart to connect an organisation.