Subject
Also called: subject or subject line
The subject of an email is a short description of the message chosen by the sender, which is displayed in the recipient's inbox. This way, the recipient gets an impression of the message content even before opening the e-mail message. The subject can also help make old messages easier to find later.
Choosing a good subject is crucial in email marketing. A catchy subject determines whether the recipient of a business email will open it or delete it unopened.