Definitions for "Subject Line"
The line in e-mail messages where you insert the subject being discussed. This is an important place to add "spin" to a marketing message.
in a letter or memo is a heading used to state the subject of the message.
A line that is part of the headers at the beginning of each email message. Mail programs invariably display the subject lines when showing a list of messages. It is widely considered a best practice for the subject line to accurately describe the contents of the message.
a great place to pique the reader's interest and command them to open your newsletter now