Cold Email Subject Lines That Get Opens
Cold email open rates average 20-30%. If yours are below that threshold, the subject line is the problem - not the message body, not the timing, not the follow-up cadence. Subject lines under 6 words get opened at 1.5x the rate of longer ones, and specificity beats curiosity every time.
Why this happens
Most cold email subject lines fail because they pattern-match to sales templates that buyers have been trained to ignore. "Following up on my last email," "Partnership opportunity," "Quick question" - these phrases have been used so many times that they register as noise before the email is opened. The buyer's brain filters them out the same way it filters display ads: automatically and without conscious effort.
The instinct to be vague or mysterious ("Thought you'd find this interesting") comes from trying not to sound salesy. But vagueness reads as template, not as curiosity. Specificity - referencing something real about the recipient's company, role, or situation - is what signals that this is a real message worth opening.
What to check first
One question cuts through everything else: are your subject lines specific enough that they could clearly not be a template? If you replaced the recipient's name with a different name and sent the same subject line to 500 people without changing a word, it's a template. Templates get ignored.
Run this diagnostic on your last 10 cold email subject lines:
- Are they under 6 words?
- Do they contain a specific reference to the recipient's company, role, or a thing they've done?
- Do they avoid "following up," "partnership," "synergy," "excited to," or "checking in"?
- Do they frame a question or observation rather than a pitch?
If any subject line fails more than one of those criteria, it's dragging your open rate down.
How to fix it
Three formulas that consistently outperform templates:
Formula 1 - Name + specific question: "[First name] - quick question about [specific thing at their company]." The specificity of the thing is what makes this work. "Quick question about Acme's onboarding flow" is specific. "Quick question about your onboarding" is a template.
Formula 2 - Observation: "Noticed [specific thing] at [company]." This requires actual research - a recent hire, a product launch, a job posting that signals a specific pain - but it opens at a rate that justifies the time. The observation signals that you did the work before emailing, which most people don't.
Formula 3 - Direct intro: "Intro: [your product] for [role at company type]." This is the most honest version. It doesn't pretend not to be a sales email. Buyers who are in the market for what you're selling will open it. Buyers who aren't won't - which is the correct outcome.
What to remove from every subject line you write: "checking in," "following up," "partnership opportunity," "synergy," "excited to share," "reaching out," "hope you're well." Each of these phrases is a signal to the buyer that this email can be safely deleted without reading.
Remove the guesswork
Open rate is one number. Reply rate, meeting booked rate, and sequence conversion rate are the numbers that matter for pipeline. RightEngagement tracks your outreach performance across the full sequence and identifies where prospects are dropping off - so you know whether you have a subject line problem, a body problem, or a follow-up problem.
Related: Once your subject lines are landing opens, see Cold Email That Gets Replies to fix what happens after they open. - RightEngagement ROI Calculator
