Skip to main content

Office 365 Email Signature Not Showing: Troubleshooting Guide

Fix Office 365 signature problems: not appearing in Outlook, duplicate signatures, blocked outbound mail, missing employees after sync and broken images.

WiseStamp for IT › Microsoft 365 › Step 12 of 12 — Troubleshooting Reference



Quick index

Symptom

Section

Signature not appearing in Outlook

section 1

Two / duplicate signatures

section 2

Outbound mail not sending (server-side)

section 3

Signature missing only on some devices

section 4

Employees missing after sync

section 5

Admin can’t log in

section 6

Images broken / oversized

section 7

"Signature too long" error

section 8


section 1 — Signature not appearing in Outlook

Work through in order:

  1. Directory connected but no deployment yet. Connecting Entra ID does not place signatures. Confirm the Outlook Add-In is connected (Deploy the Outlook Add-In) or server-side is configured (Server-Side Deployment).

  2. Employee not Active. The Add-In only signs Active employees with a Primary Signature assigned. Check the Employees page (Deploy the Outlook Add-In, Ongoing Admin Guide).

  3. Client not refreshed. Have the user restart Outlook desktop and refresh Outlook web so the Add-In loads.

  4. Add-In not propagated. After centralized deployment, Microsoft can take time to push the Add-In to all mailboxes. Confirm it shows in the Microsoft 365 admin center (Integrated apps).

  5. Default signature not selected (manual/native check).

    • Outlook desktop: File > Options > Mail > Signatures; confirm a signature is set for New messages and Replies/forwards.

    • Outlook web: Settings (gear) > View all Outlook settings > Mail > Compose and reply; enable signature for new messages and replies/forwards; Save.

  6. Email format not HTML. File > Options > Mail > Compose messages in this format = HTML.

  7. Advanced (desktop): Update Outlook (File > Office Account > Update Options > Update Now); run in safe mode (outlook /safe); repair Office (Control Panel > Programs and Features > Office > Change > Repair); reset nav pane (outlook.exe /resetnavpane).


section 2 — Two / duplicate signatures

  • Most common cause: the user has a manually pasted (copy/paste) signature in Outlook in addition to WiseStamp. Remove the manual signature in Outlook signature settings, restart Outlook.

  • Hybrid mode is designed to prevent duplicates (server-side only appends when no WiseStamp signature is detected). If duplicates persist in hybrid, confirm the client-side signature is being detected correctly and check for a stray manual signature.


section 3 — Outbound mail not sending (server-side)

This should not happen in normal operation. If it does:

  1. Emergency bypass: Exchange admin center > Mail flow > Rules > open Identify messages to send to WS SMTP > toggle off. Mail then delivers without a server-side signature.

  2. Contact WiseStamp support / your CSM for investigation.

  3. Reconnect when resolved: In WiseStamp, Integrations > Disconnect, then Connect for Microsoft Exchange and follow the prompts to re-establish the connection.

  4. Keep multiple admins with Exchange admin center access so bypass can be applied quickly.

If the automated connection shows errors, disconnecting and reconnecting the server-side solution from Integrations often clears transient connection issues.


section 4 — Signature missing only on some devices

  • Add-In only covers Outlook clients where it’s installed and signed in. Mobile mail apps that aren’t Outlook, or non-Outlook senders, won’t get a client-side signature. For universal coverage use server-side or hybrid (Setup Overview, Server-Side Deployment).

  • Confirm the device’s Outlook build meets the minimum versions (Prerequisites Checklist).


section 5 — Employees missing after sync

  • Confirm the directory integration is healthy and daily sync is enabled (Settings > Sync & Automations).

  • If using selective sync, the missing users' department/OU may be excluded — review the Sync specific selection.

  • If using Security Group sync, confirm the users are explicit, direct members of the group (no nested groups) and that the correct Group ID is in use (Sync Microsoft Security Groups).

  • Remember: auto-synced accounts remove users who no longer exist in the directory; a "missing" user may have been removed from Entra ID.

  • A manual resync can be triggered from Sync settings.


section 6 — Admin can’t log in

  1. Check for outages, then refresh the browser and clear cache/cookies; retry.

  2. Chrome extension login loops: go to chrome://extensions/, remove the WiseStamp extension, then log out and back in.

  3. Subscription lapse: verify the subscription is active; renew if needed, which restores login and signature display.

  4. Wrong audience: only owners/admins log into the main account. Employees do not log in — they use the Employee Hub.

  5. SSO issues: confirm the user is assigned to the WiseStamp app in your IdP and that SAML endpoints/RelayState match (SSO with Entra ID (SAML)).


section 7 — Images broken / oversized

  • Follow WiseStamp’s image size/quality best practices; oversized source images can render enlarged. (See the image best-practices material in the knowledge base.)

  • Confirm images are hosted/embedded as intended and that the client isn’t blocking remote images.

  • Check dark-mode rendering separately — optimize the signature for dark mode if logos disappear on dark backgrounds.


section 8 — "Signature too long" error

  • This is a known Outlook limitation handled in WiseStamp’s "Signature too long" guidance. Reduce signature size (trim embedded image weight, simplify markup) per that guidance.


When to escalate to WiseStamp support

  • Server-side mail flow failures after applying the emergency bypass.

  • Manual server-side configuration (must be enabled by support; routing code issued by support).

  • Security Group sync enablement (Group ID entered by WiseStamp).

  • SSO domain creation and metadata finalization.

  • Any IP-allowlist requirement for server-side routing — confirm the current ranges with WiseStamp support.


Related articles


Did this answer your question?