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Exchange Server Email Signature Not Working: Troubleshooting

Fix Exchange signature faults: missing in Outlook, duplicates, mail not sending, connector errors, SPF and DKIM failures, sync gaps and oversized images.

WiseStamp for IT › Exchange › 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

Server-side connection errors

section 4

Signature missing only on some devices

section 5

Employees missing after sync

section 6

Admin can’t log in

section 7

SPF "not found" / DKIM fails

section 8

"Signature too long" error

section 9

Images broken / oversized

section 10


section 1 — Signature not appearing in Outlook

  1. Identity connected but no deployment yet. Connecting Entra ID doesn’t place signatures. Confirm the Add-In is connected (Outlook Add-In Setup) or server-side is configured (Server-Side Routing).

  2. Employee not Active. The Add-In signs only Active employees with a Primary Signature.

  3. Client not refreshed. Restart Outlook desktop; refresh Outlook web.

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

  5. Default signature / format checks.

    • Outlook desktop: File > Options > Mail > Signatures — set for New and Replies/forwards.

    • Outlook web: Settings > View all Outlook settings > Mail > Compose and reply — enable for new + replies; Save.

    • Ensure Compose messages in this format = HTML.

  6. Advanced (desktop): update Outlook; outlook /safe; repair Office; outlook.exe /resetnavpane.


section 2 — Two / duplicate signatures

  • Most common cause: a manually pasted signature in Outlook alongside WiseStamp. Remove it in Outlook signature settings, restart Outlook.

  • Hybrid mode prevents duplicates (server-side appends only when no WiseStamp signature is detected). If duplicates persist in hybrid, confirm the client-side signature is detected and remove stray manual signatures.


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

  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.

  3. Keep multiple admins with Exchange admin center access for fast bypass.

  4. Re-enable the rule once resolved.


section 4 — Server-side connection errors

If you hit connection errors that block mail or signatures, disconnect and reconnect:

  1. WiseStamp Integrations > Disconnect (top-right); follow prompts.

  2. Integrations > Connect for Microsoft Exchange; follow prompts to re-establish.

This often clears transient connection issues. If it persists, contact support.


section 5 — Signature missing only on some devices

  • The Add-In covers only Outlook clients where it’s installed and signed in (and requires Exchange Online mailboxes). Non-Outlook senders won’t get a client-side signature. For universal coverage use server-side or hybrid (Setup Overview, Server-Side Routing).

  • Confirm device Outlook builds meet the minimums (Prerequisites Checklist).


section 6 — Employees missing after sync

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

  • Selective sync may exclude the missing users' department/OU — review the Sync specific selection.

  • Security Group sync: confirm explicit, direct membership (no nested groups) and the correct Group ID.

  • Auto-synced accounts remove users no longer in the directory — a "missing" user may have been removed from Entra ID.

  • Trigger a manual resync from Sync settings.

  • On-prem-only note: employee sync is not supported for on-prem; no plan supports it (Identity & Employee Sync).


section 7 — Admin can’t log in

  1. Check for outages; refresh; clear cache/cookies; retry.

  2. Chrome extension login loops: chrome://extensions/ > remove WiseStamp extension > log out/in.

  3. Subscription lapse: verify active; renew to restore login and signature display.

  4. Wrong audience: only owners/admins log into the main account; employees use the Employee Hub.

  5. SSO: confirm the user is assigned in the IdP and SAML endpoints/RelayState match (SSO (SAML)).


section 8 — SPF "not found" / DKIM fails (server-side)

SPF not found:

  • Confirm include:outbound.smtp.wisestamp.net is in your SPF and propagated.

  • SPF allows max 10 DNS lookups; flatten nested records; inspect with an SPF lookup tool.

DKIM fails after enabling server-side:

  1. Temporarily disable the WiseStamp routing rule; send a test; if DKIM passes, injection is the cause.

  2. Request your unique DKIM record from support (don’t copy one from elsewhere).

  3. Add as TXT (value begins v=DKIM1;), TTL 1 hour.

  4. Tell support so they enable signing.

  5. Re-enable the rule; send a test; confirm dkim=pass.


section 9 — "Signature too long" error

A known Outlook limitation handled in WiseStamp’s "Signature too long" guidance. Reduce signature size (lighter images, simpler markup).


section 10 — Images broken / oversized

  • Follow WiseStamp’s image size/quality best practices; oversized sources render enlarged.

  • Confirm images are hosted/embedded as intended; the client may block remote images.

  • Check dark-mode rendering separately.


When to escalate to WiseStamp support

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

  • Manual server-side config (enabled by support; routing code issued by support).

  • DKIM issuance and enabling signing.

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

  • Pure on-prem is not supported (resolves EX1/EX2): employee sync is not supported for on-prem, and no plan supports it. Do not escalate this — advise the customer to migrate identity to Entra ID (hybrid, at minimum).


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