When are plain text emails needed and which devices still use them?

Key findings

• Accessibility: Plain text emails are universally readable, ensuring that content is accessible across all email clients, devices, and user preferences, including those with visual impairments using screen readers.
• Compatibility: Many devices, particularly wearables like the Apple Watch, or older/specialized email clients, may only support plain text or a limited subset of rich text, not full HTML.
• Deliverability: Including a plain text alternative (in a multipart/alternative email) can improve deliverability by offering a spam filter-friendly version, reducing the likelihood of your email being flagged or blocked. This is often an overlooked aspect of ensuring your email campaign arrives in the inbox.
• Machine processing: For machine-to-machine (M2M) communication, such as banking alerts or system reports, plain text emails are often preferred due to their consistent, unformatted structure which facilitates automated data extraction and processing.
• Notifications: Many mobile phone notification systems and email previews (preheaders) pull content directly from the plain text version of an email, making it critical for immediate message clarity.

Key considerations

• Multipart/alternative: Always send emails as multipart/alternative, providing both HTML and plain text versions. This allows the recipient's email client to display the most appropriate version. We have a detailed article on whether you should still send multipart/alternative emails.
• Content consistency: Ensure your plain text version accurately reflects the HTML content. Discrepancies can confuse recipients and may negatively impact user experience.
• Link formatting: Links in plain text emails must be fully qualified URLs, as they won't be hyperlinked automatically. Consider using URL shorteners for long links to maintain readability. For more on this, check out Email on Acid's insights on plain text emails.
• Calls to action: Clearly state calls to action, as visual cues like buttons are absent. Use clear, concise language to guide the recipient.
• Monitoring: Regularly test how your plain text emails appear across different clients and devices. This helps identify and fix rendering issues before they impact your audience.

Key opinions

• Universal fallback: Marketers largely agree that plain text serves as a universal fallback for situations where HTML cannot be rendered, preventing emails from appearing broken or unreadable.
• Transactional uses: Plain text is frequently cited as ideal for transactional emails, like receipts or password resets, where simplicity and clarity are paramount and visual branding is less critical.
• Wearable devices: Many marketers specifically point to wearable devices, such as smartwatches, as common modern devices that primarily display plain text or a simplified rich text.
• Email-to-SMS gateways: The use of plain text is considered essential for emails routed through email-to-SMS gateways, as these systems strip out HTML formatting.
• System alerts: For system-generated alerts or reports, plain text is often preferred for its reliability in machine processing and integration with older or less sophisticated systems.

Key considerations

• Preheader optimization: The plain text version's initial lines are crucial for mobile notifications and email previews (preheaders). Marketers must optimize this content for immediate impact and clarity.
• Ticketing system compatibility: Some older or less robust ticketing and CRM systems may struggle to parse HTML emails effectively, making plain text versions vital for internal communication and record-keeping.
• User preferences: Acknowledging that some users actively choose to receive plain text emails (or have clients that default to them) highlights the importance of offering a complete experience.
• Deliverability benefits: While not a primary driver for plain text use, marketers understand that the presence of a well-formatted plain text part can contribute positively to overall email deliverability. This also relates to avoiding spam filters with plain text.
• Automation compatibility: For user-defined automations, such as those through IFTTT, plain text can be more reliable for consistent pattern matching and data extraction.

Key opinions

• MIME structure: Experts stress that a properly constructed multipart/alternative email, where the plain text part is presented first, is crucial for how email clients (Mail User Agents or MUAs) interpret and display messages, especially for previews and notifications.
• Legacy and command-line clients: While modern clients are sophisticated, experts confirm that text-based email clients such as Mutt and Alpine are still actively used and updated, requiring plain text for optimal display.
• Machine readability: The technical community emphasizes plain text's role in facilitating machine parsing of email content, which is vital for automated systems, analytics, and integrations like IFTTT that rely on consistent data structure.
• Spam filter interaction: Experts often point out that a well-formatted plain text part can positively influence how spam filters assess an email, potentially reducing the likelihood of being flagged or blocklisted as spam.
• BlackBerry compatibility: Even for devices like BlackBerry, historically associated with plain text, experts explain that their HTML rendering often occurred server-side (in the telco's BB server), highlighting a unique approach to handling rich content.

Key considerations

• RFC compliance: Adhering to RFC standards for email formatting, particularly for multipart messages, ensures maximum compatibility and proper rendering across all platforms. We have an article discussing what RFC 5322 says versus what actually works.
• Preheader generation: Understanding that many email clients derive preheaders and notifications from the plain text part means that the plain text content needs careful crafting to convey the primary message concisely.
• System integration: When integrating email sending with various external systems (e.g., ticketing, CRM, or custom automation platforms), anticipating their plain text requirement is key to seamless operations.
• Deliverability impact: While HTML features like image-to-text ratio and bold text can affect deliverability, the inherent simplicity of plain text makes it less prone to certain formatting-related deliverability issues.
• Avoiding broken layouts: By including a clean plain text version, senders mitigate the risk of emails appearing broken or unreadable to recipients whose clients cannot render complex HTML, ensuring a baseline level of message delivery. Learn more about expert opinions on email deliverability best practices.

Key findings

• Multipart/alternative: RFCs (e.g., RFC 2046) specify the multipart/alternative content type to include multiple versions of the same content, typically plain text and HTML, allowing the recipient's email client to display the best available option.
• Order preference: Within multipart/alternative, the parts are ordered from least faithful to most faithful representation, meaning the plain text version should come before the HTML version. This ensures that simpler clients can process the plain text first.
• Universal fallback: Documentation implies that plain text serves as the universal lowest common denominator for email display, guaranteeing that a message remains readable even if rich formatting cannot be processed.
• Accessibility standards: Plain text inherently adheres to basic accessibility standards, as it does not rely on visual cues or complex layouts, making it suitable for screen readers and assistive technologies.
• Non-display clients: Specifications indirectly support plain text for non-display clients (e.g., spam filters, automated processing systems) that might only parse the text content for analysis or action.

Key considerations

• Character sets: Documentation recommends specifying character sets (e.g., UTF-8) for plain text parts to ensure proper rendering of various characters across different systems. This connects to our article on whether using Base64 versus UTF-8 HTML/Text impacts email deliverability.
• Line length: RFCs (e.g., RFC 3676) suggest a maximum line length (e.g., 78 characters, with 99 characters as a limit) for plain text to ensure readability on various displays, particularly older terminal-based email clients.
• URL clarity: Explicitly writing out full URLs in plain text is crucial, as there are no hyperlinks in a pure plain text environment.
• Compliance: Including a plain text version often contributes to compliance with email marketing regulations (like CAN-SPAM) by ensuring that essential information, such as unsubscribe links, is always accessible.
• MIME boundaries: Correctly defining and closing MIME boundaries is vital for multipart/alternative messages, ensuring that email clients can accurately distinguish between the plain text and HTML parts.