Plain-Text Email

A plain-text email is a message sent as simple text with no HTML formatting, images or design elements, using the text/plain media type. For cold outreach it is the default choice because it looks like normal one-to-one mail.

Cold Email & OutreachUpdated September 30, 2026

In short

A plain-text email is simple text with no design, which makes cold emails look personal.

Key points

  1. MIME defines text/plain for simple text, and multipart/alternative for sending a plain and an HTML version together [1].
  2. RFC 3676 defines the format=flowed parameter, which lets plain-text lines wrap cleanly on different screens [2].
  3. HubSpot's tests found plain-text emails got higher open rates than HTML, and the more HTML-rich the email, the lower the opens [3].
  4. Plain text makes Open Tracking impossible, because tracking pixels need HTML; that pushes teams toward Reply Rate as the main metric.
  5. It keeps the focus on words: the Icebreaker, Value Proposition and Call to Action (CTA).
  6. Without a separate preheader, most inboxes show the start of the body as the Preview Text, so the first line doubles as a teaser.

What plain text means technically

Email content is described by MIME media types. A plain-text email uses text/plain, which carries only characters and line breaks; there are no fonts, colors, images or links other than URLs typed as text. Designed emails use text/html, often sent together with a plain version inside a multipart/alternative container so each client can pick the format it prefers [1]. Plain text has its own conventions. RFC 3676 defines format=flowed, which lets long lines reflow to fit the reader's screen, and it also describes the standard signature separator of two dashes and a space [2]. Most mailbox apps send a basic HTML version even for simple messages, which is fine as long as there is no heavy markup.

Why plain text suits cold email

Cold email should look like what it is: a message from one person to another. Colleagues do not send each other designed newsletters, so a heavily formatted email signals marketing before a word is read. Plain text also loads instantly, reads well on any device and is harder to mistake for a bulk campaign. Data backs this up. HubSpot tested plain-text against HTML emails and found that HTML reduced open rates, with more HTML-rich versions performing worse [3]. Less markup also means fewer elements that spam filters may weigh, such as image-heavy layouts or many tracked links, which helps Email Deliverability. The wording still matters, so plain text is no excuse for spammy phrasing.

Trade-offs

Plain text gives up design, images and click tracking. For cold outreach that is usually a good trade, but it changes how you measure. Without an HTML tracking pixel there is no Open Tracking, and privacy features have made opens unreliable anyway. Measure success by Reply Rate, Positive Reply Rate and meetings booked. If you need to share a link, include one, written out plainly or as a short link on your own domain, rather than several. Keep a simple Email Signature with your name, role and company. Remember that commercial email still needs the legal elements of your region, such as a postal address and an opt-out line under the CAN-SPAM Act.

Sources
  1. RFC 2046: MIME Part Two: Media Types — IETF
  2. RFC 3676: The Text/Plain Format and DelSp Parameters — IETF
  3. Plain Text vs. HTML Emails: Which Is Better? — HubSpot
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Related terms

Email Signature

An email signature is the sign-off block that tells the reader who you are and how to reach you.

Open Tracking

Open tracking uses a hidden image to guess when mail is opened, and the signal is now noisy.

Reply Rate

Reply rate is replies divided by delivered emails, and it is the metric that matters most in cold outreach.

Email Deliverability

Deliverability measures whether your email actually lands in the inbox, not just whether the receiving server accepted it.

Spam Filter

A spam filter scores each incoming message and decides whether it reaches the inbox.

Cold Email

A cold email is a first-touch message to a stranger that works when it is relevant, specific and easy to decline.

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