Preview text

An inbox row prints three things: who it is from, what it is called, and then one more line. That third line is preview text, and it is the only one of the three a sender regularly forgets to write. When it is missing the client does not leave a gap, it scrapes the first text it finds in the message body, which is how thousands of campaigns go out advertising themselves as “View this email in your browser” or, worse, as their own unsubscribe boilerplate. The words are not a bug in the mail. They are the top of the mail, read out loud by a list the sender never designed.

The vocabulary here is genuinely muddled, and Litmus draws the line worth keeping: preview text is what the inbox prints beside or under the subject, while preheader text is what a reader sees at the top of the message once it is open. The two are usually the same string, because the standard technique is one hidden element at the very start of the body, which is why the words get used interchangeably. They are still different jobs. One competes in a list against forty other rows, the other introduces a mail somebody has already decided to read.

As a design problem it has three hard edges. It is set in someone else’s type at someone else’s width, so it arrives unstyled and cannot be laid out. It is cut at a length nobody can predict, since every client and every window gives it a different allowance, which is why the usual advice is to land the meaning inside about ninety characters and treat everything after that as a bonus. And it is read as one sentence with the sender name and the subject line rather than on its own, so a preview that repeats the subject wastes the only line that could have added something.

The technique is unglamorous. Put the words in a hidden element as the first thing in the body, then follow them with enough blank characters that the client runs out of room before it reaches the real content, otherwise the navigation and the view-in-browser link leak in behind the sentence you wrote. Everything about that is a workaround for having no control over the surface, which is the honest summary of the whole medium: the copy is yours and the truncation is not.