A pre-header in emailing is a short snippet of text that appears at the top of an email, typically right after the subject line. It serves as a preview of the email’s content and is often used to entice the recipient to open the email. This brief introduction can include a summary of the email’s main message, a call to action, or any other relevant information that can pique the reader’s interest. A well-crafted pre-header can greatly increase the chances of an email being opened and read, making it an essential element in email marketing strategies.