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HTML vs Plain Text Email: Why You Send Both, and How

Send every HTML email as multipart/alternative with a real text/plain part that carries the same message and call to action, because spam filters distrust HTML-only mail and some readers and clients show only the text part.

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Philippe Kam, founder of Emailens · Published 19 Jul 2026 · Updated 28 Oct 2026

@emailens/engine 0.18.22 · data last changed 10 Nov 2026

Part of the HTML email guide · all guides

Almost every email you send is technically two emails: an HTML version and a plain-text one, bundled together as multipart/alternative. Most people never think about the text half, which is exactly why it's so often broken, and why fixing it is an easy win.

What multipart/alternative is

A well-formed email carries both a text/html part and a text/plain part. The client picks which to show: rich clients render the HTML, while text-only contexts fall back to the plain part. The two are meant to say the same thing: the plain version is a real fallback, not an afterthought.

Why a plain-text version matters: deliverability, reach, fallback

  • Deliverability. Spam filters are suspicious of emails that ship HTML with no plain-text alternative, or with an auto-generated one that doesn't match the HTML. A clean, matching text part is a small positive signal, and its absence is a negative one.
  • Accessibility and reach. Some people read in text-only clients, on smartwatches, or with assistive setups that prefer the plain part (the HTML side of that is in the email accessibility guide). Terminal-based and privacy-focused clients often show it by default.
  • Resilience. When an HTML email renders badly (images blocked, styles stripped) a readable text part is the safety net that still gets your message across.

What a bad auto-generated plain-text version looks like

Most email platforms auto-generate the text part, and the result is often rough:

  • Hidden preheader text dumped at the very top, out of context.
  • Bare URLs with no context, or link text with the destination stripped out entirely.
  • Collapsed structure: headings, lists and sections run together.
  • Leftover markup fragments or navigation the reader doesn't need.

None of that is fatal, but it reads as careless, and careless is not the impression a good email wants to make.

How to write a plain-text email

  1. Keep the links legible. Show the destination: our pricing (https://acme.com/pricing) beats a naked URL or a "click here" with nowhere to click.
  2. Preserve structure with plain text. Blank lines between sections, simple dashes for lists, and a clear sign-off do the work that HTML formatting did.
  3. Drop what doesn't translate. Hidden preheaders, tracking pixels and decorative navigation have no place in the text part.
  4. Keep it in sync. The plain and HTML versions should carry the same message and the same call to action.

Generate the plain-text version, then edit it

You don't have to write the text part from scratch. Paste your HTML into the plain-text generator to get a clean starting point (links kept inline, markup stripped) then give it a quick read and trim anything that doesn't belong. While you're preparing to send, it's also worth adding campaign tags with the UTM link builder and confirming your authentication with the SPF, DKIM & DMARC guide.

Questions

What is multipart/alternative in email MIME structure?

multipart/alternative is a standard MIME packaging format containing both text/plain and text/html parts. The recipient's email client automatically picks which part to render based on device capabilities and accessibility preferences.

Do spam filters penalize HTML emails that lack a plain-text version?

They count it against the message. Filters such as SpamAssassin are suspicious of HTML with no plain-text part, and of a text part whose content does not match the HTML.

Who reads plain-text emails in 2026?

Users on smartwatches (Apple Watch, Wear OS), subscribers using assistive screen readers or terminal-based clients, and security-conscious readers with HTML rendering disabled rely on the plain-text part.

How should links and calls to action be formatted in plain-text emails?

Avoid vague phrasing like 'Click here'. State the context of the action clearly, followed by the exact URL on its own line: 'Access your account settings: https://app.example.com/settings'.

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Also useful: Plain-Text Generator · Deliverability Checker · Subject Line & Preheader Tester

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