Your signature,
always on-brand.
Everywhere. Automatically.
OneSignature gives every employee a perfect, up-to-date email signature in Outlook — managed centrally by your team, filled with live data from Microsoft 365, and smart enough to serve the right signature to the right audience.
Hi Sarah,
Thanks for the call — I've attached the proposal and look forward to your thoughts.
Best,
Let's be honest — email signatures are a mess
They're the most-seen piece of your brand — and the most neglected. Sound familiar?
OneSignature fixes all of it. Permanently.
Three steps. No fuss.
If you can send an email, you can get OneSignature running. It disappears into the background and does its job.
Under the hood, it's refreshingly boring
A client-side engine runs inside Outlook. That's the whole trick — and it's why the privacy story is so strong.
Your user's Outlook
the OneSignature engine runs here
- Pulls profile data straight from Microsoft Graph, on-device
- Stores signatures in the user's own mailbox
- Works in classic, new Outlook, web, Mac, and mobile runtimes
Your Microsoft 365 tenant
the single source of truth
- Live name, title, department, phone and photo
- Group membership drives which template applies
- Domain-aware audience detection for internal vs external
Serious under the hood, simple on the surface
Every feature serves two people: the admin who needs control, and the employee who just wants their email to look right.
Your users' data stays where it belongs
Most signature tools copy your entire directory to their servers to do this job. We built OneSignature backwards on purpose — so that's simply not required.
No directory sync. Ever.
We don't bulk-import your users, their photos, or their contact details anywhere.
On-device by default
Profile data is fetched from Microsoft Graph on the user's device and stored in their own mailbox. Our servers see none of it.
Your call, not ours
Companies that want server-side profile refresh can opt into our on-behalf-of flow. It's off unless you turn it on.
Compliance-friendly posture
Less attack surface, fewer data flows, and a story you can defend.
Zero-server architecture
The add-in runs on the user's device, talks directly to their own Microsoft 365 tenant, and stores signatures in their mailbox. There is no “our copy of your directory” to hack, leak, or subpoena.
How does it stack up? Pretty well.
Against the hand-rolled status quo, and against the server-hungry tools that came before.
| The old way | Typical signature tools | OneSignature | |
|---|---|---|---|
| Brand consistency | Every employee a wildcard | Set once, usually central | 100% on-brand, enforced |
| Profile data freshness | Stale the day it's written | Synced periodically | Live from Microsoft 365 |
| Works on every device | Windows maybe, pray for mobile | Usually desktop-first | Windows, Mac, web, mobile |
| User data on third-party servers | N/A — it's on your machines | Yes — your whole directory | Only if you opt in |
| Per-team templates | Hand-maintained chaos | Sometimes, with effort | Group-based, with inheritance |
| Signatures for external recipients | Everyone sees the same one | Rarely supported | Automatic — full, slim, or none |
| Time to deploy | IT tickets for weeks | Days of integration | About 10 minutes, one link |
Questions? Good.
The short, honest versions of the things people ask us most.
Do employees have to install anything?
No. Your admin deploys OneSignature once from the Microsoft 365 admin center using a single manifest link — then it's available to everyone automatically, on every Outlook they use.
What happens when someone gets a promotion or changes departments?
Their signature updates itself. Profile details like title, department, and phone come live from Microsoft 365, and the signature refreshes on a regular cycle — no IT involved.
Can employees still personalize their signatures?
Yes. Anyone can open the OneSignature task pane and edit their own signature — but the admin can always regenerate from the latest company template or reset customizations.
Which Outlook apps does it work in?
Windows (classic and new Outlook), Mac, Outlook on the web, and Outlook mobile. Event-based injection needs a client that supports Mailbox 1.10 or later; older clients can still open the editor from the ribbon.
Where does user data actually live?
On the user's device and in their own mailbox. The OneSignature cloud delivers templates and policy; profile data is fetched directly from your Microsoft 365 tenant on the device. Server-side profile refresh only happens if your company explicitly opts in.
What does the WYSIWYG editor support?
All the formatting you'd expect — fonts, colors, images, tables, social icons — plus a code view if you prefer to write HTML. Saved signatures are validated so they render cleanly in email clients.
Do we have to design a signature from scratch?
No. The template gallery has 45 ready-made designs that render cleanly in every email client. Pick one, drop in your brand colors and contact details, and you're done.
Can different teams have different signatures?
Absolutely. Assign templates to groups, and group membership — including inherited membership — decides which signature each person gets, with a company default as the fallback.
Can external contacts see a different signature?
Yes — automatically. When a message goes to someone outside your organization, OneSignature switches to the outreach signature, and swaps back when external recipients are removed.
Ready to look great in every inbox?
One signature. Live data. Zero compromise on privacy. Your team can be sending on-brand email by the end of the hour.
Uses the Microsoft 365 sign-in you already have — no passwords, no new accounts.