2.Make the subject line useful.
I think we have to follow the subject line useful. A good subject line provides a useful summary of the email's content, preparing the reader quickly. Email inboxes are frequently swamped, so a good subject line helps the recipient determine the priority of your email. It also helps to prevent your email from being deleted before it has even been read. Since the subject is the first thing your recipient sees, keep it error free, concise, and avoid generic lines such as "Hi," "What's up," or the recipient's name (the latter may be blocked by anti-spam filters).