The Slippery Slope: Joseph Sugarman's One Rule That Makes Cold Email Impossible to Ignore

Joseph Sugarman sold over 20 million pairs of BluBlocker sunglasses through mail-order advertising. Before that, he sold electronic calculators, pocket organizers, and smoke detectors through full-page magazine ads that people read the way they’d read a short story.

His copy was long. Sometimes very long. A full-page ad, densely written, with no white space. In an era when advertising experts said shorter was better, Sugarman kept writing long copy, and it kept selling.

The reason it worked was a single principle he called the slippery slope.

“Your readers should be so compelled to read your copy that they cannot stop reading until they read all of it, as if they were sliding down a slippery slope.”

The mechanism: the only purpose of the headline is to get you to read the first sentence. The only purpose of the first sentence is to get you to read the second. The only purpose of the second is to get you to read the third. Every element in the copy exists solely to move the reader one step further down the slope, until they reach the end having been pulled rather than pushed through the entire piece.

This principle, applied to cold email, changes how you write every element of every message.

The subject line’s only job

In Sugarman’s framework, the subject line has one job and one job only: get the first line of the email opened and read.

Not to summarize the email. Not to promise a benefit (though that can help). Not to be clever. Get the first line read.

This sounds obvious until you see how many subject lines violate it.

A subject line like “Increasing Your Revenue With Our B2B Lead Generation Platform” tries to do too much. It’s explaining the pitch before the email is opened. It’s asking the reader to evaluate whether they want the thing before they’ve had the chance to be interested in it.

A subject line like “quick question” or “saw something about [Company]” does exactly one thing: creates enough curiosity or personal relevance that the reader opens to find out what the question or observation is.

The subject line is the top of the slope. It just needs to be steep enough that the reader can’t help sliding.

What makes a subject line steep in the Sugarman sense:

Incompleteness. “The reason your cold emails aren’t working” creates an open loop. The brain doesn’t like open loops. It seeks closure. To get closure, the reader has to open the email.

Personal relevance. “[Company]‘s outbound setup” signals that whatever is inside is specifically about them, which is more interesting than anything generic could be.

Specificity that implies a story. “9% reply rate on 500 contacts” implies that something happened. The reader wants to know what.

None of these require the subject line to sell anything. They just need to make the first line of the email feel like the necessary next step.

The first sentence: the most important copy you’ll write

Sugarman was obsessive about first sentences. In his courses and writing, he returned to this again and again: the first sentence must be so short and so simple that it is almost impossible not to read it.

Not interesting, exactly. Easy. Effortless to read.

He would write first sentences of five or six words. Sometimes fewer. Not because short was always better, but because a very short first sentence has almost no friction. The eye moves through it before the reader has consciously decided to start reading.

Once they’ve read the first sentence, they’re already on the slope. Momentum takes over.

In cold email, the first line that appears in the preview pane is your version of Sugarman’s first sentence. The reader sees it before they open the email. It determines whether they open at all.

Most cold email preview text is wasted. The email opens with “Hi [Name], I hope this message finds you well” and the preview reads “Hi Sarah, I hope this message finds you w…” which is about as compelling as watching paint dry.

What would Sugarman put in the preview?

The observation that’s so specific to this person that they can’t not open to find out where you’re going with it.

“Noticed something about [Company]‘s outbound setup.”

“Three of your SDR posts just closed.”

“Your reply rates might be higher than you think.”

Short. Specific. Incomplete. It ends mid-thought, which means the brain seeks closure, which means they open the email.

Seeds of curiosity

Sugarman had a technique he called “seeds of curiosity.” Throughout a piece of long copy, he would plant small forward references to things he hadn’t explained yet.

“But before I tell you that, let me explain why most people get this completely wrong…”

“The surprising part comes later, and it’s not what you’d expect.”

“I’ll show you the exact setup in a moment.”

Each seed is a tiny unresolved loop. The reader is compelled to keep reading to close the loop. The effect compounds: the more seeds that are open simultaneously, the harder it is to stop reading.

In cold email, which is short by necessity, you don’t have room for many seeds. But you can use one or two to structure the pull through the email.

Example:

Your cold email reply rates are probably better than your open rates suggest. Let me explain.

Most teams we look at have a deliverability problem they don’t know about yet. Emails are being sent, open rates look acceptable, but a significant portion of sends are landing in the promotions tab or spam. The replies that would have come from those contacts never arrive.

There’s a simple diagnostic you can run in about 10 minutes to see exactly what’s happening. Happy to walk you through it if this sounds familiar.

The first sentence is a seed: it promises an explanation that hasn’t come yet. The second paragraph builds the context. The third is the CTA, but it’s structured as the payoff to the seed. The reader has been pulled to the ask rather than pushed.

Compare this to the same email without the seed:

We help B2B SaaS companies improve their cold email deliverability. If your open rates are lower than you’d like, it might be a deliverability issue.

We have a diagnostic process that can identify the problem. Want to book a call?

This version is accurate but flat. There’s no slope. Each sentence is a new, separate claim. There’s no forward pull. The reader can stop at any point without losing anything.

Psychological triggers and why they work in cold email

Sugarman’s book Triggers documented 30 psychological factors that influence buying decisions. Not tricks. Factors that reflect how human decision-making actually works. Several of them are directly applicable to cold email.

Involvement

Sugarman found that involving the reader in the copy, making them do a small action mentally or physically, dramatically increased engagement and conversion.

In print ads, he used involvement devices like: “Circle the number that best describes your situation” or “Read the description below and see if it matches what you’re experiencing.”

In cold email, involvement looks like a question the prospect is implicitly answering as they read.

“Does this match what you’re experiencing?” or “You’ve probably seen this pattern” or “Here’s the thing most VP Sales in your position would rather not admit” all invite the reader to position themselves relative to the copy. Once they’re doing that, they’re involved. Involvement is the opposite of passive reading.

Credibility

Sugarman understood that credibility is fragile and critical. Anything that undermines it, even subtly, kills the conversion.

In cold email, credibility is built by:

Specific numbers instead of vague claims (a Sugarman and Hopkins principle alike)
Acknowledging limitations or tradeoffs (“this approach works best for teams above 50 employees”)
Not overpromising (“this isn’t magic, but here’s what we consistently produce”)
Mentioning recognizable clients or reference points that the prospect can verify

And destroyed by:

Superlatives with no evidence (“the best,” “the most,” “revolutionary”)
Claims that are too big to be believed (“10x your pipeline”)
Fake personalization that’s obviously automated (“I’ve been following your remarkable journey, [First Name]”)
Pressure tactics that feel manipulative (“this offer expires tonight”)

Credibility in cold email is hard to build and easy to lose. Every word choice either adds to it or takes from it.

The emotional buy, justified by logic

Sugarman’s most quoted insight: “People buy for emotional reasons and justify with logic. Your job is to provide both.”

The emotion comes first. The prospect has to feel something: curiosity, recognition of pain, aspiration, anxiety about a problem. Logic comes after: the reasons why what you’re saying is credible and the decision to respond is rational.

Cold email that leads with logic and skips emotion (“our platform has 47 features including inbox rotation, A/B testing, and CRM integration”) produces nothing. The prospect has no emotional foothold. They haven’t felt anything yet. Logic without emotion is a list of facts that doesn’t compel action.

Cold email that leads with emotion and provides no logic is also weak (“imagine the meetings you could book if your cold email actually worked”). It’s evocative but not grounded. There’s nowhere to land.

The structure that works:

Emotion first: the specific pain, the recognition, the desire (“your reply rates drop around month two of most campaigns”)
Credibility bridge: the reason this is true (“it’s almost always a deliverability decay issue that compounds as sending volume increases”)
Logic: the evidence that you’ve solved this before (“we fixed this for a Series A security company in three weeks, and their reply rate went from 1.1% to 6.3%”)
Low-friction CTA: easy next step that doesn’t require them to be fully sold yet (“worth 15 minutes to see if the same issue exists in your setup?”)

Each step in this structure serves the one before it. The emotion hooks. The credibility bridge makes it believable. The logic justifies the emotional interest. The CTA makes it easy to act.

Why short cold emails need the slope even more than long ones

Sugarman is famous for long copy. It’s tempting to think his principles apply only to long-form content and not to the short cold emails that work best in outbound.

The opposite is true. Short copy needs the slope more, not less.

In a long piece, you can recover from a weak sentence. The reader has enough momentum that a flat line doesn’t stop them. In a short email of 75 to 125 words, every sentence is critical. There’s no room for filler. The slope has to be steep from the first word to the last, because there are so few words.

This means:

The first line cannot be wasted. No “I hope this message finds you well.” No self-introduction. The slope starts immediately.

Each sentence must earn the next. Read your email and ask: after this sentence, would a skeptical, busy person keep reading? If the answer is no, rewrite the sentence or cut it.

The last line before the CTA must make the CTA feel like the natural next step. It should not be a non-sequitur. The CTA should feel like the logical arrival point of everything that came before it.

The CTA itself should be a slope. Not “let me know if you’re interested” (a dead end that requires them to initiate). “Worth 15 minutes this week to look at your setup?” pulls them toward a specific action that feels manageable.

The Sugarman edit: how to apply the slippery slope to your existing emails

Take a cold email that’s underperforming. Apply this process:

Step 1: Test the first sentence. Is it so short and simple that it would be almost rude not to read it? If it’s more than 10 words, consider whether it can be cut or shortened. If it starts with “I” or the company name, rewrite it to start with something about the prospect.

Step 2: Find the forward pull. Does any sentence in the email create an unresolved question that the next sentence answers? If not, can you restructure so that one sentence creates a small anticipation that the next resolves?

Step 3: Check the emotional hook. Does the first paragraph make the prospect feel something? Recognition of a problem, curiosity, mild anxiety about a situation they’re in? If not, what’s the emotional entry point for this prospect and how can you surface it faster?

Step 4: Check the logic. After the emotional hook, is there a specific, credible reason to believe what you’re claiming? A number, a mechanism, a named example?

Step 5: Check the slope to the CTA. Does the last line before the ask set up the ask as the natural next step? Or is the CTA a separate, disconnected request?

Step 6: Read it out loud, end to end. Does it pull? Does it feel like a slope or does it feel like a list of assertions? Would you keep reading if you received this cold?

The bottom line

The slippery slope is not a copywriting gimmick. It’s a description of how reading actually works.

Attention is not given. It’s borrowed, moment to moment, sentence by sentence. Every time the reader’s eye reaches the end of a sentence, they decide whether to continue. Your job is to make that decision automatic, each time, until they reach the reply button.

Sugarman figured this out selling BluBlockers in magazine ads. The channel was different. The principle is identical.

Make the first sentence easy to read. Make the second sentence the necessary result of the first. Keep pulling until they respond.