Outlook for iOS and Android keeps its own signature in the app settings, separate from Outlook on the computer. For a consistent signature you have three options: an Outlook add-in that inserts it automatically, an Exchange Online rule that adds it on the server, or setting it by hand on every phone.
Why doesn't Outlook on the phone use the company signature?
Outlook on the desktop and on the web keeps signatures in the mailbox, while the phone app has its own setting (Settings → Signature). By default it says something like "Get Outlook for iOS", and employees rarely change it. The result: messages from phones leave without logo, title and phone — or with a signature someone typed by hand years ago.
How do you set the same signature on every phone?
There are three ways: each employee types it in, an Outlook add-in inserts it automatically while writing, or an Exchange Online rule adds it on the server to every outgoing message. Only the Exchange rule works in every app, and only the add-in shows the signature while writing.
1. Set it by hand on every phone
Each employee types their signature in the app. It works, but depends on each person, images and formatting are limited, and every phone must be updated when a title or number changes.
2. An Outlook add-in (automatic insertion)
Recent versions of Outlook for iOS and Android can run an add-in when a new message, reply or forward is started, and the add-in inserts the signature. The user sees it while writing and can check it before sending. Requirements:
- the administrator deploys the add-in centrally (Microsoft 365 → Integrated apps),
- users run an up-to-date Outlook app,
- Microsoft rolls changes out to phones with a delay (up to a few hours).
3. An Exchange Online rule (server-side)
A transport rule adds the signature to every outgoing message on the server, whatever the device or app — including the built-in Mail app on iPhone. Drawbacks: the sender does not see the signature while writing, in replies it is added at the end (below the quote), and Exchange supports a limited set of directory fields.
| By hand | Outlook add-in | Exchange rule | |
|---|---|---|---|
| Sender sees the signature | yes | yes | no |
| Works in every app | no | Outlook only | yes |
| Directory data | no | yes, all | partly |
| Short reply signature | no | yes | no |
| Admin effort | high | one-time deployment | one-time setup |
How SignetMail handles it
SignetMail supports both automatic methods, and you can combine them:
- The Outlook add-in inserts the signature on every new message in new Outlook, on the web, on Mac and in Outlook for iOS and Android.
- The Exchange Online rule is created by a script you run once. Messages that already got a signature from the add-in on the computer or in the browser are marked, so the rule does not add it twice.
Recommendation: the add-in for computers, the browser and Outlook on phones. Use the Exchange rule as a safety net for apps that do not run add-ins (such as the built-in Mail app on iPhone).
Frequently asked questions
Doesn't the desktop signature sync to the phone?
Outlook on the desktop and on the web sync signatures with each other, but the phone app has its own setting. That is why you need one of the methods above.
Does the logo work on phones?
Yes, if the image is on a public HTTPS address. With the Exchange rule the logo is linked rather than embedded, so some recipients only see it after allowing images.
How much does it cost?
SignetMail is in public beta and free with every feature until the beta ends, including the add-in and the Exchange rule.
Try SignetMail for free
Free during the public beta, with every feature and no card. We help pilot companies with the setup.