Email Signature Keeps Disappearing? Here’s How to Stop It

Outlook: Roaming signatures overwriting your local setting

If your Outlook signature disappears or reverts — especially after a few hours or after restarting Outlook — roaming signatures are almost certainly the cause. This is a Microsoft 365 feature introduced to sync signatures across devices, and it works by pulling the signature from Outlook Web App (OWA) and overwriting whatever you’ve set locally in the desktop client.

The fix isn’t complicated once you know about it: set your signature in OWA, not in desktop Outlook.Here’s how:

1. Open a browser and go to outlook.office.com. Sign in with your work Microsoft 365 account.
2. Click the gear icon (Settings, top right).
3. Go to Accounts → Signatures.
4. Create or update your signature here. Set it as the default for new messages and replies.
5. Click Save, then reopen desktop Outlook. Within a few minutes, your desktop Outlook signature will update to match what you set in OWA.

If you want to disable roaming signatures entirely (and go back to managing the desktop signature locally), this requires admin access via PowerShell. An IT admin can run:

Ask your IT admin for help with this. The Outlook signature guide has the full context on roaming signatures and Microsoft 365 settings.

Outlook: Profile corruption

A corrupted Outlook profile doesn’t usually cause Outlook to stop working entirely — it causes weird, intermittent problems. Signatures that appear and disappear randomly, settings that don’t save, or a signature that works in some compose windows but not others are all symptoms of profile corruption.

Profile corruption can be caused by: abrupt Outlook shutdowns (power outage, force-quitting), a failed Windows update that modified registry entries mid-write, or disk errors on the drive where your profile data lives.

How to diagnose

Run the Office configuration diagnostic. Open a Run dialog (Win+R), type:

This resets the navigation pane without touching your email data or signatures. If this fixes the issue, it was a profile configuration problem. If not, the more thorough fix is creating a new Outlook profile (covered in our Outlook signature not showing guide — Fix 10).

Outlook: Windows / Office update resets signature defaults

I’ve seen this happen repeatedly: a major cumulative Windows update or an Office channel update resets the “default signature” setting to (none), even though the signature files in %AppData%\Microsoft\Signatures are still intact.

The signature isn’t deleted — it’s just no longer set as the default. After any significant Windows or Office update, it takes 30 seconds to check:

Go to File → Options → Mail → Signatures. Check that the dropdowns under “Choose default signature” still show your signature for New messages and Replies/forwards. If they’ve been reset to (none), select your signature again and click OK.

Outlook: Group Policy override from IT

In managed enterprise environments, IT departments can deploy Group Policy Objects (GPOs) that control Outlook behavior, including signatures. A GPO can either prevent you from setting a signature at all (the field is greyed out) or can periodically push a required signature that overwrites whatever you’ve set.

Signs of a GPO override:

• Your signature reverts at a predictable interval — e.g., every time you log in to your Windows account, or every morning.
• The signature field in Outlook Options is greyed out or has a lock icon.
• The revert happens only on your work PC but not on a personal device with your work email.

You can’t override a GPO yourself — that’s the point of GPOs. Contact your IT department and ask whether there’s a signature management policy in place and whether you can be excluded from it or whether they can update the policy to include your preferred signature.

Gmail: Browser cache wiping your signature

If your Gmail signature saves fine but then disappears after you clear your browser cache, this is the cause. Gmail stores certain user preferences — including signatures — both server-side and in local browser storage. Clearing browser data (cache + cookies + local storage) can cause Gmail to temporarily lose the locally cached version until it re-syncs from the server.

The good news: this is usually a short-term problem. If you save your signature and it appears to work but then disappears after closing the browser, try this:

1. Open Gmail and go to Settings → General → Signature.
2. Make a small edit to your signature (add a space, then remove it) to force a save.
3. Scroll all the way to the bottom of the Settings page and click Save Changes.
4. Close the browser completely, reopen, and go back to Gmail Settings to verify it persisted.

If the signature consistently disappears after browser cache clears, check for a browser extension that may be clearing cache automatically (some privacy extensions do this on close). For full Gmail signature troubleshooting, see the Gmail signature not working guide.

Gmail: Multiple devices and account switching

Gmail’s desktop signature (set via Settings in a browser) and the Gmail mobile app signature (set in the app’s own settings) are completely independent. If you set your signature in Gmail on your laptop and then check your email from your phone, you’re looking at the mobile app signature — which may be blank or different.

The other common confusion is account switching. If you use Gmail with multiple Google accounts (personal and work, for example), each account has its own signature settings. Opening Gmail on a new device and signing into the wrong account means you see that account’s signature (or none at all).

To make sure all devices show your correct signature:

• Set your desktop signature in Gmail Settings → General → Signature (this applies to Gmail on any browser on any computer when logged into that account).
• Set your mobile signature separately in the Gmail app: menu → Settings → your account → Mobile Signature. Mobile signatures are plain text only.
• If you have multiple accounts, do this separately for each account.

Apple Mail: “Always match my default message font” — the main offender

This is the single most reported Apple Mail signature problem and it’s been around for years. There’s a setting in Apple Mail that, when checked, forces your signature to use the same font as your default message compose font. The result: any custom font or formatting in your signature gets overridden. Your carefully styled signature starts rendering in whatever font you use to write emails.

How to turn it off

On macOS Sonoma and later (Mail 17+):

1. Open Mail. Click Mail in the menu bar, then Settings.
2. Click the Signatures tab.
3. At the bottom, uncheck “Always match my default message font.”

On macOS Ventura and earlier (Mail Preferences):

1. Open Mail. Click Mail → Preferences (or Cmd+Comma).
2. Click the Signatures tab.
3. Uncheck “Always match my default message font.”

For complete Apple Mail signature setup including how to add HTML signatures, see the Apple Mail email signature guide.

Apple Mail: macOS update reset

Major macOS updates (e.g., a jump from macOS Sonoma to macOS Sequoia) can reset Apple Mail preferences, including signature settings. The signature files themselves usually survive in the Library folder, but the assignment of which signature belongs to which account, and the “always match font” preference, can get reset to defaults.

After any macOS update where Mail behaves differently:

1. Open Mail → Settings (or Preferences) → Signatures.
2. Check that your signature still appears in the center column. If not, click the + button to recreate it.
3. Drag the signature to the account(s) in the left column to reassign it.
4. Uncheck “Always match my default message font.”
5. Close Settings and compose a test email to verify the signature appears.

Apple Mail signature files live at ~/Library/Mail/V10/MailData/Signatures/ (the V-number may differ based on your Mail version). Back up this folder before major macOS upgrades if you have custom HTML signatures you want to preserve.

General: Antivirus and security software interference

Enterprise endpoint security software — Norton, Bitdefender, Sophos, CrowdStrike, and others — sometimes scans outgoing emails and modifies their content. In most cases this is fine, but some configurations strip HTML content or external image links from email signatures as a security measure.

The signs: your signature looks correct in the compose window and in your Sent folder, but recipients see a stripped version with no formatting or no images. Or your signature files on disk keep being flagged or quarantined.

How to diagnose

Send a test email to your personal Gmail address from your work email. View the source of the email (in Gmail: three dots → Show original). Compare the signature HTML in the source to what you have in your signature settings. If content has been stripped, security software is the likely cause.

Temporarily disable email scanning in your security software (if you have permission to do so) and send another test. If the signature arrives intact, email scanning is the issue. Contact your IT security team to whitelist your email signature content or adjust the scanning rules.

General: Shared computers and multiple Windows user profiles

If you work from multiple computers — an office PC, a laptop, a hot desk — or if you share a computer with others, you may encounter a problem that looks like a disappearing signature but is actually a different Windows user profile that doesn’t have the signature configured.

Each Windows user account stores Outlook data and signatures independently. Signatures in %AppData%\Microsoft\Signatures on one user account are not visible to other user accounts on the same machine.

The fix is to set up the signature on each computer and each user account where you email from. If that’s a lot of machines, consider setting it up in Outlook Web App (OWA) instead — since roaming signatures sync to all devices when logged in with your Microsoft 365 account, you only need to set it once there.

For the quickest multi-device setup, the NeatStamp editor saves your signature to your account. Sign in from any computer, copy the HTML, and install it in 30 seconds. The Outlook setup guide and Gmail setup guide both have step-by-step instructions for installing on a new machine quickly.

Frequently asked questions

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