Email Signature Analyzer
Check your email signature for HTML bloat, image issues, broken links, and spam triggers that hurt deliverability.
Paste the HTML source of your email signature, or plain text. Everything is analyzed in your browser.
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Score Breakdown
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Why Your Email Signature Affects Deliverability
Your email signature is appended to every message you send. If it contains bloated HTML, oversized images, or suspicious links, it adds weight to every single email. Spam filters evaluate the entire message body, including the signature, when calculating risk scores. A heavy or poorly coded signature can push otherwise clean emails over the spam threshold.
Most people never think about their signature from a deliverability perspective. They add logos, social icons, banners, legal disclaimers, and tracking links without realizing each element increases the HTML weight and complexity that spam filters analyze. A signature that looks professional to humans can look suspicious to algorithms.
Email Signature Best Practices
The best email signatures are lightweight and simple. Keep your HTML under 20KB, use no more than one or two small images with proper alt text, and limit yourself to three or four links. Use table-based layouts with inline CSS for maximum compatibility across email clients.
Key guidelines:
Keep it short. Your signature should contain your name, title, company, and one or two contact methods. Everything else is optional weight.
Use inline CSS only. Many email clients strip <style> tags entirely. If your signature relies on external or embedded stylesheets, it will break in Outlook, Gmail, and most other clients.
Avoid web fonts. Custom fonts loaded via @font-face or Google Fonts will not render in email clients. Stick to system fonts like Arial, Helvetica, Georgia, or Verdana.
Optimize images. If you include a logo, keep it small (under 50KB), hosted externally (not base64 embedded), and always include width, height, and alt attributes. Missing alt text is a common spam signal.
Common Signature Mistakes That Trigger Spam Filters
Image-only signatures are one of the biggest deliverability mistakes. When your entire signature is a single image with no text, spam filters see a message with a poor text-to-image ratio. This is a pattern commonly associated with spam and phishing emails.
Shortened URLs from services like bit.ly, t.co, or ow.ly are another red flag. Spammers use URL shorteners to hide malicious destinations, so spam filters treat them with suspicion. Always use full, direct URLs in your signature.
Excessive links are also problematic. Every link in your signature is another URL that spam filters need to evaluate. Social media icons with links, website links, calendar booking links, and promotional banners can quickly add up to 10+ links in a single signature. Keep it to the essentials.
How to Create a Deliverability-Friendly Signature
Start with a simple table-based layout. Tables are the most reliable structure across all email clients, including Outlook's notoriously limited rendering engine. Use a single table with one or two rows, and keep nesting to a minimum.
Write all your styles inline. Instead of using a <style> block, put your CSS directly on each element: <td style="font-family: Arial, sans-serif; font-size: 14px;">. This ensures your formatting survives even the most aggressive email client processors.
Host your images on a reliable CDN or your own domain. Avoid base64-encoding images directly into the HTML, as this dramatically increases the signature size and can trigger spam filters. A 10KB logo that is base64-encoded becomes roughly 13KB of HTML text.
Test your signature across clients using a tool like Litmus or Email on Acid, or simply send test emails to Gmail, Outlook, Yahoo, and Apple Mail to verify it renders correctly everywhere.
Frequently Asked Questions
Can my email signature actually cause emails to go to spam?
Yes, though rarely on its own. A signature with bloated HTML, image-only content, shortened URLs, or excessive links adds to the overall spam score of every email you send. If your sender reputation is already borderline, a heavy signature can be the factor that tips your messages into the spam folder. Think of it as cumulative risk: the signature alone probably will not cause spam placement, but combined with other factors it can.
How large should my email signature be?
Aim for under 20KB of HTML. Most well-optimized signatures fall between 5-15KB. If your signature exceeds 50KB, it is almost certainly adding unnecessary weight to every email. The total email size (body + signature + images) should ideally stay under 100KB for optimal deliverability.
Should I use images in my email signature?
One or two small images (like a company logo) are fine as long as they have proper alt text, explicit width and height attributes, and are hosted externally rather than base64-encoded. Avoid image-only signatures where all the content is embedded in a single graphic. Many email clients block images by default, so your signature should still be readable as plain text.
Are social media icons in signatures a problem?
Social icons themselves are not a problem, but they typically add 4-8 additional images and links to your signature. Each link is a URL that spam filters evaluate. If the icons are small, externally hosted, and link directly to your profiles (not through shorteners or trackers), they are generally fine. Just be aware of the cumulative impact on your signature weight and link count.
Does this tool upload my signature to a server?
No. This tool analyzes your email signature entirely in your browser using JavaScript. Nothing is uploaded to our servers. The only data sent is a summary of your score and basic metrics (HTML size, image count, link count) if you choose to unlock the full report with your email address.