Guide

Email Signature Testing & Debugging

How to test your email signature across different clients and fix common rendering issues.

Testing Checklist

Before rolling out your new email signature, test it in these clients:

Gmail
Web + Mobile
Outlook
Desktop + Web + Mobile
Apple Mail
macOS + iOS
Yahoo Mail
Web
Samsung Email
Android

How to Test

  1. Send to yourself: Send a test email to your own account(s) — Gmail, Outlook, Yahoo
  2. Send to a colleague: Ask them what they see on their device
  3. Check mobile: Open the test email on your phone (both iOS and Android)
  4. Check with images off: Disable image loading and see what remains visible
  5. Check reply/forward: Reply to the email and verify the signature doesn't break in the thread
  6. Check dark mode: Switch your email client to dark mode and verify readability

Common Issues & Fixes

🖼️ Broken Images

Cause: Images hosted on an expired/blocked URL. Fix: Host images on a reliable CDN or your own website. Avoid embedding base64 images.

📐 Layout Breaking in Outlook

Cause: Outlook uses Word's rendering engine, not a web browser. Fix: Use HTML tables for layout, inline CSS, avoid flexbox/grid.

📱 Too Wide on Mobile

Cause: Fixed-width tables too wide for mobile. Fix: Use max-width instead of width, keep total width under 600px.

🌙 Invisible in Dark Mode

Cause: Dark text on transparent background becomes invisible. Fix: Add background colours, use transparent-safe logo formats (PNG with padding).

↔️ Extra Spacing

Cause: Different email clients add default margins/padding. Fix: Reset margins and padding on table cells. Use cellpadding="0" cellspacing="0".

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Pre-Tested Email Signatures

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