Is a plain text email version important for email deliverability?

Key findings

• Accessibility: Plain text versions are primarily beneficial for accessibility, assisting screen readers and users with visual impairments, ensuring content is readable even without full HTML rendering.
• Deliverability impact: For major inbox providers, the direct deliverability benefits of a plain text part in a multipart/alternative email are often considered minimal today. Modern filters are sophisticated enough to handle HTML emails. However, some legacy systems and B2B filters might still penalize HTML-only emails or offer a slight advantage to those with a plain text alternative.
• Fallback: A plain text version serves as a fallback for email clients that either cannot render HTML, or have images disabled by default. This ensures the message content is still conveyed.
• Spam filtering: Some older spam filtering technologies, like Spam Assassin, may assign negative scores to emails lacking a plain text part, potentially impacting deliverability on systems using such filters.
• Client rendering: Most modern consumer email clients default to rendering the HTML part of a multipart message and do not typically display the plain text version unless specifically requested by the user, or if HTML rendering fails.

Key considerations

• Effort vs. reward: Manually creating a plain text version can be time-consuming, leading some marketers to question if the minimal deliverability gains justify the effort. Automated tools often generate a plain text fallback, but quality can vary.
• HTML quality: Ensuring high-quality HTML that is accessible and renders well across clients is often more impactful than relying solely on a plain text fallback for deliverability or accessibility. For more insights on how HTML impacts deliverability, see our article on email code quality and size.
• Multipart/alternative structure: Emails should ideally be sent as multipart/alternative, containing both HTML and plain text parts. This allows email clients to display the most appropriate version for the recipient.
• Image-only emails: While a plain text version can compensate for issues with image-only emails, focusing on proper image-to-text ratio and alt text is generally a better strategy for deliverability and engagement.

Key opinions

• Accessibility focus: Many marketers primarily view plain text as an accessibility feature for screen readers, rather than a crucial deliverability component.
• Minimal deliverability benefits: The consensus among many high-volume senders is that direct deliverability benefits from plain text versions are minimal with modern email clients and filters, especially for major providers like Gmail and Outlook.
• B2B considerations: Some acknowledge a potential minor deliverability bump in B2B environments where organizational filters might be stricter or have remote images disabled.
• Manual effort concern: The time-consuming manual process of creating a plain text version in certain platforms is a significant deterrent for many marketers, questioning its worth against perceived minimal impact.
• No noticeable data: Some marketers with large client bases and high volumes haven't observed sufficient data to justify the recommendation for proper multipart/alternative emails based purely on deliverability performance.

Key considerations

• Automated generation: Platforms that automatically generate plain text versions from HTML can mitigate the manual effort, making inclusion more feasible even if the direct deliverability impact is small.
• Recipient experience: While many clients show HTML, a plain text version ensures a basic message is still received even if there are rendering issues. Consider when plain text emails are still needed.
• Impact on conversion: While not directly tied to deliverability, a poor plain text fallback could negatively impact conversion if a user sees it. Marketers should consider the holistic user experience. More information on this can be found in our article: Does including a plain text version improve deliverability and conversion?
• Email quality assurance: It's important to preview both HTML and plain text versions to ensure the plain text fallback is readable and formatted logically, with clear links.

Key opinions

• Diminished value: The direct deliverability value of multipart/alternative emails (and thus the plain text part) is seen as having decreased over time for most consumer mail clients.
• HTML preference: Most modern email clients and screen readers are now capable of handling HTML effectively, making the plain text fallback less critical for rendering or accessibility than it once was, provided the HTML is well-structured.
• Legacy filter impact: Some legacy spam filters, notably Spam Assassin, still prefer or penalize the absence of a plain text part, suggesting continued relevance for certain recipients.
• No consumer rendering: It's noted that almost no consumer mail client will natively render the text/plain part of a multipart message.
• Evolving standards: The email ecosystem is constantly changing; what was once 'gospel' regarding MIME/multipart emails may no longer be universally applicable for deliverability.

Key considerations

• Mechanical conversion: If a plain text version is created, it should ideally be generated mechanically from the HTML to ensure consistency. If this results in an unreadable plain text, the HTML itself likely needs to be optimized for better accessibility and fallback.
• Inbox behavior: While some older systems may still prefer a plain text version, major inbox providers like Gmail and Yahoo largely rely on more advanced filtering mechanisms.
• Recipient diversity: Despite changes, a portion of the recipient base may still use older clients or have settings that benefit from a plain text fallback, making its inclusion a robust strategy for broad reach. More details on different email types and their deliverability can be found here.

Key findings

• MIME standard: The MIME (Multipurpose Internet Mail Extensions) standard specifies how emails with different content types, like HTML and plain text, should be structured. The multipart/alternative format allows email clients to choose the most appropriate version.
• Spam filter preference: Documentation for various spam filters often mentions checking for the presence and content of the plain text part. A mismatch or absence can sometimes increase spam scores.
• Robustness: Including a plain text version makes emails more robust against various rendering environments, from basic text-only clients to those with images disabled.
• Email client behavior: Most modern clients will prioritize the HTML part, but the plain text provides a necessary fallback. Email on Acid provides insights on when plain text emails should be used.
• Best practice: Across various email marketing platforms and deliverability guides, including a plain text version is still considered a fundamental best practice for broad compatibility.

Key considerations

• Content consistency: The plain text version should ideally mirror the HTML content as closely as possible to maintain message integrity, especially concerning critical information and calls to action.
• Link handling: Links in the plain text version should be fully visible URLs, as they cannot be hidden behind anchor text like in HTML. This can sometimes make plain text emails appear less tidy.
• Code quality: The overall quality of your email's code, including both HTML and plain text, impacts how well it is processed by mail servers and clients. For more details, consult our resource on email code quality and size impact on deliverability.
• Tracking limitations: Open and click tracking for plain text emails relies on different mechanisms (e.g., appended tracking parameters to links) compared to HTML, which uses pixel tracking. Campaign Monitor provides useful details on tracking plain text emails.