Definition

A preheader is the short preview text that appears next to or below the subject line in most inboxes. It is the second thing a reader sees before deciding whether to open.

Most email tools let you set it directly. If you do not, the inbox shows the first words of the email body, which is often something like 'View this email in your browser'. A good preheader adds to the subject line instead of repeating it. It is not visible once the email is open, so it exists only to earn the click in the inbox.

A B2B example: the subject line reads 'Three contract clauses that stall deals'. The preheader adds 'and the one sentence that fixes each'. Together they tell the reader what they will get and why it is worth their time.

Why it matters for B2B email

A preheader is free space in a crowded B2B inbox. Busy readers scan subject and preview text together, and a wasted preheader makes an otherwise strong email look like a template. Treat it as the second half of the subject line, and it quietly lifts open rates on every send.

Related terms

Subject line A subject line is the short line of text that shows in the inbox before an email is opened.
Open rate Open rate is the share of delivered emails that were opened.
Newsletter A newsletter is a regular email sent to your whole list, or a large segment of it, on a schedule.

Part of the B2B email marketing glossary. Last updated 2026-10-08.