Why Do Email Clients Strip HTML?
Understanding why email clients strip HTML for security and compatibility
Table of Contents
Why Do Email Clients Strip HTML?
Email clients strip HTML for security and compatibility reasons: to prevent malicious code execution (JavaScript, iframes), to block security vulnerabilities (forms, interactive elements), to ensure compatibility across email clients (removing unsupported features), to prevent phishing attacks (blocking dangerous HTML), and to maintain email client performance (removing complex features).
Email clients strip JavaScript tags, iframes, forms, unsupported HTML5 tags, external stylesheets, and other potentially dangerous or incompatible HTML. Understanding why HTML is stripped helps create email HTML that renders correctly across email clients.
Use our HTML validator to identify HTML that may be stripped and ensure email client compatibility.
Security Reasons
1. Prevent Malicious Code
Email clients strip JavaScript and iframes to prevent malicious code execution, XSS attacks, and security vulnerabilities.
2. Block Security Threats
Clients strip forms, interactive elements, and potentially dangerous HTML to prevent phishing attacks and security threats.
3. Protect Users
HTML stripping protects users from malicious emails, phishing attempts, and security vulnerabilities.
4. Prevent Attacks
Stripping dangerous HTML prevents email-based attacks, malware distribution, and security exploits.
5. Security Best Practices
HTML stripping follows security best practices, protecting users from email-based threats.
Compatibility Reasons
1. Ensure Compatibility
Email clients strip unsupported HTML to ensure emails render correctly across different email clients and devices.
2. Remove Unsupported Features
Clients remove HTML5 features, modern CSS, and unsupported tags that may not work in all email clients.
3. Maintain Consistency
HTML stripping helps maintain consistent rendering across email clients by removing incompatible features.
4. Performance
Stripping complex HTML improves email client performance and rendering speed.
5. Email Standards
HTML stripping aligns with email HTML standards and best practices for email client compatibility.
What Gets Stripped
Email clients typically strip the following HTML:
JavaScript
<script>tags- Inline JavaScript
- Event handlers (onclick, onload, etc.)
Iframes and Embeds
<iframe>tags<embed>tags- External content embeds
Forms and Inputs
<form>tags<input>tags<button>tags
External Stylesheets
<link>tags for CSS- External style references
Unsupported HTML5
- Modern HTML5 tags
- Unsupported CSS features
Avoiding HTML Stripping
1. Use Email Client-Compatible HTML
Use table-based layouts, inline styles, and email client-compatible HTML to avoid HTML stripping.
2. Avoid Stripped Tags
Avoid JavaScript, iframes, forms, and unsupported HTML5 tags that email clients strip.
3. Use Inline Styles
Use inline styles instead of external stylesheets to prevent CSS stripping.
4. Validate HTML
Use our HTML validator to identify HTML that may be stripped.
5. Test in Clients
Test emails in multiple email clients to verify HTML isn't stripped and renders correctly.
6. Follow Best Practices
Follow email HTML best practices to ensure HTML isn't stripped and emails render correctly.
