Classic Outlook reads signatures from files on the computer; the new Outlook for Windows reads them from the cloud mailbox, like Outlook on the web. Scripts and tools that write signature files therefore have no effect in the new Outlook, and neither do COM add-ins. What works is an Outlook add-in (a web add-in) that inserts the signature while composing, in classic Outlook, the new Outlook, on the web and on phones.
What is different in the new Outlook?
| Classic Outlook | New Outlook for Windows | |
|---|---|---|
| Where signatures live | Files on the computer (the Signatures folder in the user profile), and in recent versions also in the mailbox | In the cloud mailbox, same as Outlook on the web |
| COM and VSTO add-ins | Supported | Not supported |
| Web add-ins (Office add-ins) | Supported | Supported, including automatic launch on a new message |
| Scripts that write signature files | Work | No effect on the signature |
Why is the signature missing in the new Outlook?
Many companies have managed signatures with a logon script (PowerShell or VBScript), Group Policy, or a tool that writes HTM, RTF and TXT files to each computer. The new Outlook doesn't read those files. When an employee switches to the new Outlook, the signature is empty, or it's whatever they once set on the web.
How do you keep one signature in both Outlooks?
1. An Outlook add-in
A web add-in starts on its own when someone writes a new message, a reply or a forward, and inserts the signature. It works in classic and new Outlook for Windows, Outlook for Mac, the web, iOS and Android. An admin deploys it centrally in the Microsoft 365 admin center (Integrated apps).
2. An Exchange Online rule
A rule appends the same text to every outgoing message, whatever the client. The sender doesn't see it while writing, it can't contain each person's details, and in replies it lands below the quoted text. Good for a legal footer, not for a full signature.
3. Manual setup in the new Outlook
Each employee enters a signature in Settings → Account → Signatures. Because it is stored in the mailbox, it also applies on the web, but every change has to be made for each person.
How SignetMail handles it
- The Outlook add-in inserts the template signature in classic and new Outlook, on the web and on phones.
- The Windows agent for classic Outlook also writes the signature files, so people who don't use add-ins or are offline still have it.
- Both take data from the same directory, so the signature is the same whichever Outlook someone uses.
Frequently asked questions
Does a logon signature script work with the new Outlook?
No. The script writes files to the computer, while the new Outlook reads signatures from the cloud mailbox. You need an Outlook add-in or a tool that sets the signature in the mailbox.
Can I hold off the switch to the new Outlook until signatures are sorted?
Microsoft lets admins control the switch with policies for now, but it is moving everyone to the new Outlook over time. It is better to set up signatures in a way that works in both.
Does a signature add-in also work in Outlook on phones?
Yes, in up-to-date apps for iOS and Android. More in Signatures in Outlook on the phone.
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