In email marketing, the header refers to the top portion of an email message, which typically includes the sender's name, email address, subject line, and preheader text. The header is the first thing a recipient sees when they receive an email, and it is important because it sets the tone for the rest of the message and can impact whether the recipient opens the email or not.
The sender's name and email address are important components of the header because they establish the sender's identity and credibility. The subject line is also a crucial part of the header, as it gives the recipient an idea of what the email is about and can influence their decision to open it or not. Preheader text, which appears as a short summary of the email's content in the inbox preview, can also help entice the recipient to open the email.