When Outlook Loses Your Signature
Why it vanishes, and how to stop rebuilding it.
The Short Answer
Microsoft now runs two signature systems at once. New Outlook and Outlook on the web store signatures in your mailbox in the cloud. Classic Outlook stores them as files on your PC. They do not reliably sync.
So a signature you saved is not lost — it is in the other system, or it was overwritten by it.
Build a signature you can keep a copy of →Which Problem Do You Have?
| Symptom | Cause |
|---|---|
| Gone after restarting Outlook | Roaming vs local storage conflict |
| Listed in settings, never inserted | Not assigned to New messages |
| Appears on replies but not new mail | Only one of the two dropdowns set |
| Formatting and logo stripped | Message composing in Plain Text |
| Fine on desktop, missing on web | The two systems are out of sync |
| Reverts to an old version | Cloud copy overwriting the local one |
Cause 1: Two Systems, One Mailbox
Roaming signatures live in your Microsoft 365 mailbox so they follow you between devices. Classic Outlook predates this and reads local files instead. When both are in play, whichever writes last wins, and the other appears to have lost your work.
Fix: pick one as the source of truth. The reliable approach is to set the signature in Outlook on the web, save it there, then let new Outlook pick it up. If you live in classic Outlook, keep your signature local and accept that the web version may differ.
Cause 2: Saved But Never Assigned
The most common false alarm. Your signature is sitting in the list, correctly formatted, and Outlook is not inserting it because neither dropdown points at it.
Fix: in signature settings, set both New messages and Replies/forwards. Do it for every account in the profile — the setting is per account, so adding a second mailbox silently gives you a blank assignment.
Cause 3: The Message Is Not HTML
Plain Text strips everything. Rich Text mangles it and breaks images for anyone outside your organisation. Only HTML renders a signature the way you built it.
Fix: set HTML as the default for new messages in Outlook options, and check the Format Text tab on any message that looks wrong.
Where Classic Outlook Keeps Them
On Windows, signatures are files here:
%APPDATA%\Microsoft\Signatures
Each one is stored three times — .htm, .rtf and .txt — so Outlook can serve whichever message format you use. Copying this folder is how you move signatures to a new machine, and copying it somewhere safe is the cheapest backup you will ever make.
The Fix That Actually Holds
None of the above stops Microsoft changing the sync behaviour again. What does help is keeping the signature HTML somewhere Outlook cannot touch, so restoring it is a paste rather than an hour of rebuilding.
The Email Signature Generator produces a table-based signature with inline styles — the layout email clients actually render consistently — and gives you both the rendered signature and the raw HTML to copy. Save that HTML in a note somewhere. Next time Outlook loses it, you are ten seconds from having it back.
It runs in your browser, so your name, direct line and address are not uploaded anywhere to produce a block of HTML.
A Note on Logos
Images in signatures break more often than text does, because many clients block remote images by default and a logo hosted on a server you later change becomes a broken icon on every email you ever sent.
If the logo is small, embedding it as a data URI with the Image to Base64 converter avoids the hosting problem entirely — though note that some clients, Outlook desktop included, are inconsistent about rendering data URIs, so test before rolling it out.
Frequently Asked Questions
Why does my Outlook signature disappear every time I restart?
Almost always because new Outlook and classic Outlook use two different storage systems. New Outlook and Outlook on the web use roaming signatures held in your mailbox in the cloud, while classic Outlook reads local files on your PC. The two do not reliably sync, so a signature saved in one can be invisible or overwritten in the other.
My signature is in settings but never appears on new emails. Why?
It is saved but not assigned. Outlook keeps two separate dropdowns, one for New messages and one for Replies and forwards, and a signature can exist with neither selected. Set both explicitly, for each email account, since the assignment is per account rather than global.
Where are classic Outlook signatures stored on disk?
In your user profile under AppData, Roaming, Microsoft, Signatures. Each signature is saved three times, as .htm, .rtf and .txt. Copying that folder to another machine moves your signatures across, and backing it up is the simplest insurance against losing them.
Why does my signature appear as plain text with the formatting stripped?
The message is being composed in Plain Text or Rich Text rather than HTML. Only HTML format preserves fonts, colours, links and images. Check the Format Text tab on the message itself, and set the default for new messages in Outlook options.
How do I stop losing it again?
Keep the signature HTML somewhere outside Outlook. When it vanishes, pasting a known-good copy back takes a few seconds instead of rebuilding from memory. That is the practical fix, because the underlying sync behaviour is not something you control.