How do I write a subject line people will open?

The mechanism is straightforward. A subject line that withholds the point produces an open, and then the reader discovers the contents did not justify the opening. Do that three times and the pattern is learned, and the same list that opened at a healthy rate stops opening at all. Accurate subject lines produce fewer opens from people who were never interested and more from people who were, which is the trade you want.

Be specific rather than clever. A subject naming what the message contains, in plain words, outperforms wordplay for the same reason that plain website copy outperforms slogans: the reader is scanning quickly and deciding whether this is relevant to them. Cleverness requires a moment of interpretation, and that moment is where the message gets skipped.

Keep it short enough to display, which on a phone is roughly the first six or seven words. Mail applications truncate, and a subject whose meaning arrives at word twelve is a subject nobody read. Front load the substance and let anything decorative fall off the end.

Write it after the message rather than before. A subject drafted first tends to describe what you intended to say, and the message frequently ends up being about something else. Writing it last means it describes what is actually in there, which is the entire job.

Avoid the constructions that trigger filtering and scepticism in equal measure. Excessive capitals, multiple exclamation marks, the word free repeated, and anything implying urgency that does not exist. These affect deliverability and they also read as a business that learned email from a template rather than from thinking about the reader.

Match the subject to the sender name, which people evaluate together. For a small business the sender should almost always be your name or your name and the business rather than a department, because a message from a person is opened more readily than one from an entity, and it is honest at your scale.

Test on your own list rather than trusting general guidance, since email is the one channel where a small business can get an answer quickly. Splitting a send between two subject lines produces a usable result within a day, and it is the only realistic place most first year businesses can practise this meaningfully.

Be careful about judging by open rate alone, which has become unreliable since mail providers began pre loading images on behalf of users. A rise in opens without any change in replies or clicks may be measuring privacy features rather than attention, and the more honest signals are whether people respond and whether anybody unsubscribes after a particular message.

And remember that the subject line is doing considerably less work than the sender relationship. A list of people who chose to hear from you and find the messages useful will open a plain subject. A list that does not will not open a good one, and no amount of craft in seven words compensates for content that has not been worth reading.

Keep a record of which subjects performed well on your own list rather than relying on general guidance, because the pattern for your audience is frequently specific to them. A dozen sends is enough to notice whether your readers respond better to questions, to plain descriptions, or to something naming a number, and that observation is worth more than any list of formulas.

Avoid reusing the same subject across sends, because mail applications thread by subject and a new message can be collapsed into an old conversation the reader has already dismissed.