What is a sales email subject line?
The short line a reader sees in the inbox before deciding whether to open the email.
What it means
The subject line is the short line a reader sees in the inbox, next to your name, before they decide whether to open the email. In sales it has one job: tell the reader what the email is about in a way they recognize as worth a look.
It is not a headline or an ad. The best sales subject lines read like something a colleague would send, and they match what the email actually says.
What it means for a sales email
Gong and 30 Minutes to President's Club (30MPC) looked at cold subject lines that got opened. The ones that did well looked like internal notes: a few words, normal capital letters, and a real priority for the reader. Boomerang found that subjects in all capital letters read like yelling.
Keep the subject short enough to show in full on a phone, with the important words first. That limit is a writing practice, not a study result. Skip hype, buzzwords, and vague teasers like quick question.
Research mentioned above: Gong / 30MPC, 2025Boomerang, 2017
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