Opens are vanity — half of them are robots anyway. Replies are the game. And replies come from emails that read like a sharp colleague wrote them, not a sequence tool. Here’s the anatomy.

The subject line: small, lowercase, internal

The best cold subject lines look like they came from inside the company: two to four words, lowercase, zero punctuation tricks. pipeline math, re: your hiring page, quick one. You’re not trying to sell in the subject — you’re trying to not look like marketing.

What kills you: ALL CAPS words, emoji, “{firstName}, exciting opportunity!”, and anything that smells like a newsletter.

The first line: proof of homework

The reader decides in one line whether this is mass spam or a message for them. So spend the line proving you did homework:

“Saw you just opened the Austin office — guessing outbound for the new team starts from zero.”

Not flattery (“Love what you’re building!”), not biography (“My name is X and I’m the founder of…”). An observation specific enough that it couldn’t be pasted into a thousand emails. If you use AI to draft these, our prompt library has openers built around exactly this rule.

The body: one problem, one proof, under 90 words

Cold emails die of obesity. The discipline:

One problem, stated in the reader’s vocabulary — not your feature list.
One proof point, concrete and unembellished: “we got a 9-person agency from 2% to 7% reply rate in six weeks” beats three paragraphs of adjectives.
Under 90 words total. It gets read on a phone, between meetings, by someone who didn’t ask for it. Respect that.

The ask: answerable with one word

“Do you have 30 minutes Thursday?” is a calendar negotiation. “Worth a look?” is answerable from a phone in one second. Lower the activation energy: interest first, logistics after they say yes.

Follow-ups: add, never bump

Most replies come from follow-ups — but only the ones that add something. The rules:

Never send “just bumping this.” It converts goodwill into spam reports.
Each follow-up brings one new thing: a different angle, a relevant resource, a sharper proof point.
Three to four touches, then a graceful exit. The breakup email (“closing the loop — if X ever becomes a priority, this is where I am”) often out-replies everything before it.
Stop instantly on reply. Nothing torches a warm conversation like a robot follow-up arriving after a human answered. (Norbelys stops sequences automatically the moment a real reply lands.)

Then: measure replies, not opens

Write two versions of your subject or first line, send both, and let real replies pick the winner — that’s the one metric machines can’t inflate. It’s how A/B testing works in Norbelys, and it’s how you get honestly better with every campaign, instead of optimizing for whatever Apple’s prefetcher liked this week.