What Is HTML in an Email?

What Is HTML in an Email?

HTML in an email is the HTML (HyperText Markup Language) code used to format and style email content, similar to HTML used in web pages but with important restrictions and differences. HTML emails allow rich formatting including colors, fonts, images, links, tables, and layouts.

HTML emails are typically sent as multipart messages with both HTML and plain text versions. Email clients display the HTML version when supported, falling back to plain text for clients that don't support HTML.

Extract and analyze email HTML using our extract email HTML tool, and validate HTML code with our HTML validator.

HTML Email Structure

Basic Structure

HTML emails use standard HTML structure with HTML, head, and body tags, but with email-specific considerations:

• HTML document structure
• Inline CSS styles (required for email compatibility)
• Table-based layouts (for better email client support)
• Image references (absolute URLs, not local files)
• Limited CSS support (many CSS features not supported)

Multipart Messages

HTML emails are typically sent as multipart MIME messages containing:

• HTML version (rich formatting)
• Plain text version (fallback for text-only clients)
• Attachments (if any)

Email-Specific Requirements

HTML emails must follow email-specific requirements:

• Inline styles instead of external stylesheets
• Absolute URLs for images and links
• Table-based layouts for compatibility
• Limited CSS support
• Email client-specific considerations

Email HTML vs Web HTML

HTML in emails differs significantly from HTML used in web pages due to email client limitations and security restrictions.

CSS Support

Email clients have limited CSS support. Many CSS features work in web browsers but not in email clients. Inline styles are required for reliable rendering.

JavaScript

JavaScript is not supported in emails for security reasons. Email HTML cannot include JavaScript code.

External Resources

External stylesheets and scripts are not loaded. All styles must be inline, and images must use absolute URLs.

Layout Methods

Table-based layouts are more reliable than CSS-based layouts in email clients. Modern CSS layout methods may not work.

Client Modifications

Email clients may modify, strip, or rewrite HTML for security and compatibility reasons, affecting how emails are displayed.

HTML Email Features

Formatting

• Colors and fonts
• Text styling (bold, italic, underline)
• Headings and paragraphs
• Lists (ordered and unordered)

Images

• Inline images (using absolute URLs)
• Image alt text for accessibility
• Image sizing and alignment

Links

• Hyperlinks to web pages
• Email links
• Styled link appearance

Tables

• Table-based layouts
• Data tables
• Table styling

Limited Features

Some features have limited or no support:

• Advanced CSS (flexbox, grid, animations)
• JavaScript
• External stylesheets
• Complex layouts

Extracting Email HTML

Extracting HTML from emails is useful for analysis, troubleshooting, and learning:

Why Extract HTML

• Analyze email structure and code
• Troubleshoot rendering issues
• Learn HTML email techniques
• Validate HTML code
• Check for spam triggers

Extraction Methods

Use our extract email HTML tool to extract HTML from email files (.eml, .msg) or email source code.

HTML Validation

After extracting HTML, validate it using our HTML validator to check for errors and compatibility issues.

Analysis

Analyze extracted HTML for:

• HTML structure and validity
• CSS usage and compatibility
• Image references and URLs
• Link structure
• Email client compatibility