The heading which best exemplifies the format for an e-mail subject line is Join the festivities on earth day
What is an Email Format?
THis refers to the structure and arrangement which is given to an e-mail before it is written and sent to a receiver.
Hence, we can see that the heading of an e-mail is important because it is the first thing a receiver sees and hence, it is good to write it in formal language such as "Join the festivities on earth day"
Read more about e-mails here:
https://brainly.com/question/24506250
