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Troubleshooting

This guide covers solutions to the most common issues with MailLighter.

Add-in Not Visible in Ribbon

Cause

The add-in may not be loaded, or the ribbon group may be collapsed.

Solutions

  1. Check it’s installed: Go to Home → Get Add-ins → My Add-ins and verify MailLighter is listed
  2. Restart Outlook: Close and reopen Outlook to reload add-ins
  3. Check ribbon customization: Right-click the ribbon → Customize Ribbon and ensure MailLighter is enabled
  4. Reinstall: Remove the add-in from My Add-ins and reinstall from Marketplace

Buttons Are Greyed Out

Cause

MailLighter commands are only available when composing an email (replying, forwarding, or creating a new message).

Solutions

  1. Start composing: Reply to, forward, or create a new email
  2. Check compose mode: The MailLighter dropdown appears only in compose mode
  3. Restart Outlook: If the issue persists, restart Outlook

Content Not Fully Removed

Cause

Some email clients generate non-standard HTML that may not be fully parsed by MailLighter’s processing.

Solutions

  1. Try Full Cleanup: Use the “Full cleanup” command which applies all operations
  2. Check the email format: MailLighter works best with HTML emails. Plain text emails have limited formatting to process
  3. Report the issue: If a specific email format consistently fails, report it on GitHub or contact us

Sideload Issues (Developers)

Add-in Fails to Load After Sideloading

On Windows, the Outlook desktop app (from Microsoft Store) may block localhost connections. You need to add a loopback exemption:

  1. Open PowerShell as Administrator
  2. Run:
CheckNetIsolation LoopbackExempt -a -n="Microsoft.OutlookForWindows_8wekyb3d8bbwe"
  1. Restart Outlook and try sideloading again

Build Errors

If npm start fails:

  1. Ensure you have Node.js 18+ installed
  2. Delete node_modules and reinstall:
rm -rf node_modules
npm install
  1. Check for port conflicts (the dev server uses port 3000 by default)

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