An email with a dull subject line is like a book with a boring title. You know it is there, but you might not exert effort to read it because it does not connect with you. So, you just leave it where it is, unread and unopened.

The same goes with cold email marketing. When sending an email, you must ensure that aside from a killer message, your subject line must also be interesting enough to catch the attention of your prospect. Because in reality, people judge emails just by looking at the subject line.