Preview Text

Preview text, also called preheader text, is the snippet of an email that inbox apps show next to or below the subject line before the message is opened. It is either taken from the first lines of the body or set as hidden text at the top of the email.

Cold Email & OutreachUpdated September 30, 2026

In short

Preview text is the short snippet readers see under the subject line, and it acts as a second subject line.

Key points

  1. Most email clients show a preview snippet; the amount varies by app and settings, from none to several lines [1].
  2. Litmus recommends keeping important preview text under about 90 characters because you cannot control how much appears [1].
  3. In a Plain-Text Email, the preview is simply your first line, which makes the Icebreaker do double duty.
  4. Marketing emails often use hidden preheader markup in an HTML email; in cold email that markup can look like bulk mail [2].
  5. Preview text, Subject Line and sender name together drive the open decision, although Open Rate is hard to measure since Apple Mail Privacy Protection [3].

How preview text works

When an inbox lists a message, it shows the sender, the subject and, in most apps, a short excerpt of the body. By default that excerpt is the first readable text in the email. Marketers who send designed HTML messages often add a hidden preheader element at the very top of the body so they can control the excerpt independently of the visible design. Litmus documents how widely support varies: some clients show no preview at all, while others can show several lines, depending on device and user settings [1]. Because of that range, the first 40 to 90 characters are the part you can most rely on being seen. Anything longer is a bonus.

Preview text in cold email

Cold emails are usually plain text, so there is no separate preheader: the preview is your opening sentence. That is a strong argument for starting with something about the reader rather than "Hi, my name is". A specific first line tied to the prospect's situation works as a second subject line and makes the whole email feel personal before it is opened. Hidden HTML preheaders are better left to newsletters, since heavy formatting is one of the traits of promotional marketing email that sets bulk mail apart from one-to-one messages [2]. Keep your first line honest too: under the CAN-SPAM Act a misleading subject is a problem, and a misleading preview undermines trust the same way.

Measuring the effect

Teams used to test preview text by watching open rates. That has become unreliable. Apple introduced Mail Privacy Protection in 2021, which loads remote content, including tracking pixels, privately in the background, so many opens are recorded whether or not a person looked at the email [3]. As a result, Open Tracking overstates engagement for a large share of recipients. For cold email, a better test of preview text and subject lines is the Reply Rate and the Positive Reply Rate. If you run A/B Testing, change one element at a time and allow enough sends per variant for the difference to be meaningful.

Sources
  1. The Ultimate Guide to Email Preview Text — Litmus
  2. HTML email — Wikipedia
  3. Apple advances its privacy leadership with iOS 15, iPadOS 15, macOS Monterey, and watchOS 8 — Apple Newsroom
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Related terms

Subject Line

The subject line is the inbox headline that decides whether your email gets opened and must match what is inside.

Icebreaker

An icebreaker is the first, personal line of a cold email that proves you did your homework.

Open Rate

Open rate estimates how many recipients opened an email, but privacy features now inflate it.

Plain-Text Email

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

A/B Testing

A/B testing sends two versions to similar groups and keeps the one that measurably performs better.

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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