Subject lines and openers

Treat the subject line and opener as a handoff. The subject line earns the open, and the first line keeps the recipient reading.^{1, 2} A pitch can lose before the recipient reaches the offer: announcing a service, proposal, or free item gives a stranger a reason to delete the email.³ A cold email is opened, read, and replied to in that order, and each step has its own gate.⁴

Draft the subject line

Start by deciding what the recipient should understand during the inbox scan. Keep the subject line narrow enough for that job and leave the rest of the persuasion to the message.

Use short, plain, specific language that reads like internal mail.⁵ Give the recipient a credible reason to open and a small amount of curiosity. The subject line should show relevance while the body carries the full offer.^{6, 7}

Keep the line compact. An analysis found that salesy subject lines reduced open rates by as much as 17.9 percent, while subject lines with one to four words outperformed longer ones.⁸ Short wording still needs a clear reason to matter. A vague line may be brief, but it gives the reader little to act on.

Keep the wording honest. Honesty can improve click-through rates and increase the number of opened emails.⁹ Check the promise against the message underneath it. A subject line that compresses the pitch gives away the offer and sets an expectation the body may fail to fulfill.¹⁰

Continue with the opener

The opener picks up where the inbox line stops. Write it so the reader can continue without changing context.

A cold email introduction consists of the subject line and the first one or two body sentences, and its job is to make the prospect read the next sentence.¹¹ Subject lines and opening lines should work together.¹² Carry the same reason for attention into the body, then add the context the reader needs to continue.

A version of a generic opener tailored to the company can still work.¹³ Use the company detail to make the opening relevant, then let the next sentence explain why it matters to the recipient. The opener earns its place when the body follows naturally from the subject.

Keep the opening free of a sudden change in direction. If the subject creates interest around a specific issue, the first sentence should stay with that issue. If it introduces a person or company detail, the next sentence should explain why that detail matters to the recipient.

The first sentence should make the next sentence feel like a continuation. Rewrite when the reader has to reset between the subject and the body.

Review the message in inbox order

Read the pair in the same order the recipient meets it. Wording problems show up when you read the message as a scan instead of a finished email.

The first couple of lines are what the prospect sees while deciding whether to open the email.¹⁴ The subject line determines whether the message registers during an inbox scan.¹⁵ Read the subject by itself before reading the body. It should give enough context for an open without explaining the whole offer.

Then read the opener against the subject. Check that the body pays off what the subject promises. The subject line sets expectations for what the reader will see after opening¹⁶ Ask yourself, "Would I open this email based on the subject line I wrote?".¹⁷

Judge the handoff with replies as well as opens. Apple Mail Privacy Protection affects roughly 55 to 60 percent of email opens, so many reported opens are pixel loads without a human behind them.¹⁸ Emails with research-backed personalization received reply rates of 17 to 18 percent, compared with 7 to 9 percent for basic or generic sends.¹⁹ Use the reply signal to decide whether the opener carried its promise into the body.

What not to do

These mistakes break the handoff or make the results hard to interpret. Keep this list beside the draft.

• Do not default to headline style simply because cold email subject lines are commonly written like headlines.²⁰
• Do not use bare openers such as "quick question" or "thought this might be useful," because those phrases can signal automation.²¹
• Do not use spam-trigger words, ALL CAPS, or exclamation marks, which can keep the message out of the inbox entirely.²²
• Do not turn the opener into a pitch, since pitching in a cold email can cause reply rates to fall by as much as 57 percent.²³