How Sponja Hit 10x the Average Cold Email Reply Rate with Smartlead

Roee Tsur will be the first to tell you he had no business running cold email.

Not because he is not smart. Not because he does not understand systems. Roee has spent fifteen years building software, leading engineering teams, and solving hard technical problems as a CTO. He is exactly the kind of person who figures things out.

But cold email? That was someone else's job. A marketer's job. A growth person's job. The kind of job that belongs to someone who has spent years obsessing over reply rates and subject line tests and ICP definitions.

Roee had none of that background. What he had was a product he believed in, a pipeline he needed to build, and no budget to hire someone else to do it.

Sponja helps businesses that run webinars solve a problem most of them do not even realise they have. When a webinar ends, most companies send the same follow-up email to everyone who attended, whether they were glued to their screen the entire time or opened the tab, muted it, and made coffee. Sponja changes that. It analyses attendee intent and engagement in real time, scores every participant, and drafts personalised follow-up sequences tailored to where each person actually was in the conversation.

The product is genuinely useful. But useful products still need customers to find them.

Roee decided to find those customers himself, through cold email, using a platform he had never used before, in a discipline he had never practiced.

He chose Smartlead. His very first campaign produced Sponja's very first paying customer.

TL;DR

Roee Tsur, CTO of Sponja, used Smartlead to build and validate cold email as a growth channel from scratch, with no prior outbound experience and no dedicated marketing hire. Here is what that produced:

• First paying Sponja customer acquired from a single cold email
• 50%+ reply rate on their best-performing campaign
• 5 to 10% average reply rate across all campaigns
• Reply rates and open rates that left peers in the marketing industry astonished
• Full sending infrastructure managed solo alongside a full CTO workload
• AI-personalised copy built on prospect signal, mirroring Sponja's own product logic
• Zero critical support failures across the entire engagement

Why Sponja Chose Smartlead as Their First and Only Cold Email Platform

Roee approaches decisions the way engineers do: research first, commit once you have enough signal, do not waste time second-guessing a clean decision.

He did his market research. He looked at what was available. He landed on Smartlead.

"Smartlead was our first selection when we decided to try cold emails. We did some market research and decided to start with Smartlead."

He found it through an AI search, most likely Gemini. Not a referral from a colleague. Not a paid ad. A founder asking the right questions and the product surfacing as the right answer.

Two things made the decision easy. First, the warm-up was automatic. Second, the pricing was right there on the website, transparent and predictable, so he could model what scaling would cost before he spent a single dollar.

He tried the free trial. Liked what he saw. Moved to paid. No sales pressure. No convincing required. The product did the work.

The Problem With Managing Cold Email Infrastructure as a Solo Technical Founder

Here is the thing about cold email that nobody tells you until you are already in it.

The writing is the easy part. The infrastructure is where most people quietly fail.

Managing sending accounts, keeping inboxes healthy, avoiding spam flags, understanding which domains are warming properly and which are silently drifting toward the spam folder. For most people, that is a full-time job on its own. For Roee, who was already doing a full-time CTO job, it was a problem that needed to be solved without adding hours to his week.

He is honest about where his expertise ends.

"I'm a startup founder. At Sponja I'm the CTO. I know the mechanics of the system, but I'm not a growth hacker. I'm not a marketer."

Smartlead took the infrastructure weight off his plate. The warm-up ran automatically. The pricing was predictable. The onboarding was self-serve and clear enough that he did not need to speak to anyone to understand what he was getting.

"My pain point was mainly managing the infrastructure. Smartlead helps with the automatic warm-up. And I also looked for predictability in pricing when scaling, which was very clear through your self-served onboarding flow and publicly listed pricing pages. It ticked all the boxes."

The Three Things That Made the Operation Work

Roee is not the kind of person who activates every feature because it exists. He used what solved his actual problems and built from there.

Automated warm-up with health scoring and notifications

The warm-up ran itself. Health scores gave him a clear read on each account without manual checking. And when something broke, he found out before it cost him anything.

"I get the score which tells me which account is healthy or not healthy. I get notifications when something is wrong. I had one account whose password changed, so Smartlead got locked out. I got a notification, quickly set it up, and didn't miss anything."

One notification. Thirty seconds to fix. Zero lost replies. That is what good infrastructure looks like in practice.

The unified inbox

When you are sending across multiple accounts, replies scatter. A positive response in an inbox you forgot to check is a deal that goes cold for no reason. The unified inbox put everything in one place.

"The combined unified inbox, I think you call it that, is a great feature. It is a must. It is really really easy to manage all the inboxes through that one."

Per-inbox limit controls and analytics

When deliverability signals shifted, Roee could adjust limits per inbox and use the analytics to understand why. No guesswork, no waiting for someone else to diagnose the problem.

"I like that I can scale up or down the limits of each inbox so I can control the spam rate. I can improve it with the great analytics that Smartlead gives."

The SmartAssistant Became His Cold Email Consultant

Most founders without an outbound background solve this problem one of two ways. They hire someone, or they spend weeks reading every cold email resource they can find and hope something sticks.

Roee did neither. He used the Smartlead SmartAssistant, and he used it extensively, not just for setup questions but for strategy.

"I used the SmartAssistant a lot during implementation. I got instant replies instead of waiting for a human or reading all the documentation. I got straight answers, correct and on time. Besides that, it was like a great consultant. It helped me understand the benchmarks, what limits I should put on each address, how to phrase my emails."

Think about what that actually means for a first-time outbound sender. Instead of spending weeks building up intuition through expensive trial and error, Roee had something that could answer a cold email strategy question at 11pm on a Tuesday, accurately, immediately, without judgment.

For a technical founder who learns by asking good questions and getting specific answers, that was the equivalent of having an experienced outbound consultant sitting next to him through the entire setup.

One Cold Email. One Paying Customer. Proof of Concept Validated.

This is the number that matters most for any early-stage startup. Not the open rate. Not the health score. Not the average reply rate across campaigns.

The first customer.

"We got the first customer of Sponja actually from a completely cold email. It was a cold email sent to a valid prospect, generated with AI, but it was hitting the right pain point at the right time for that customer, and it converted to the first paying user."

One email. Right prospect. Right signal. Right moment. Paid customer.

For a CTO who came into cold email with healthy scepticism about whether it would work for a technical B2B SaaS product with a specific ICP, that result was not just a win. It was the answer to a question he had been holding since he started.

The channel works. When the infrastructure lands emails in the inbox and the copy is built on something real, the channel works.

Notable Achievements

These are the results Sponja has produced through cold email on Smartlead:

50%+ reply rate on their best campaign. A highly targeted niche list with copy matched precisely to the audience's pain. Every email landed in the primary inbox. Every prospect who opened it found a message that felt written for them specifically.

5 to 10% average reply rate across all campaigns. Across a body of work where every campaign tests a different prospect source and different messaging, the floor is consistently strong.

First paying customer acquired from cold email. A single AI-generated email, sent to the right prospect at the right moment, converted to Sponja's first paying user. The channel validated itself on the very first attempt.

Reply rates and open rates that astonished the marketing industry. When Roee shared his numbers with peers in marketing, the reaction was disbelief. Not because the numbers were exaggerated. Because most people running cold email have never seen results like these and do not know they are possible.

"When I tell other people in the marketing industry our reply rates and our open rates, they're astonished by that."

Full infrastructure managed solo. No dedicated growth hire. No outbound agency. One CTO, one platform, and a system that ran itself well enough to produce results that industry veterans found hard to believe.

50% Reply Rate on Their Best Campaign. Peers in Marketing Could Not Believe the Numbers.

Every campaign Roee runs tests a different prospect source and different messaging, so he does not compare them directly. But across the board, the results have been strong enough to stop conversations.

The best campaign tells its own story.

"Our most successful campaign had a little bit over 50% reply rate. It was very successful. It was quite niche regarding the list we used and the messaging. It was very strong. So we achieved 50% reply rate. That means everyone got it to their inbox and it was good messaging so they opened it."

Fifty percent. Half of every person contacted replied. In a channel where most teams celebrate five percent.

The average across all campaigns sits between 5 and 10%. That range reflects what every serious cold email practitioner understands: list quality and targeting precision set the ceiling. Infrastructure determines whether you ever reach it.

Smartlead handled the infrastructure. Roee set the ceiling.

Why Roee's Outreach and Sponja's Product Are Built on the Same Principle

There is something that stands out when you look closely at how Roee builds his email copy.

He uses AI to draft personalised emails based on signals collected on each prospect. Not name and company. Not job title. Signals. Observable, specific data points that tell you something real about where that person is right now and what they care about.

That is exactly the same principle Sponja applies when generating follow-up sequences for webinar attendees. Personalisation driven by observed behaviour, not by template fields.

The founder's outbound strategy and the product he is selling are the same idea expressed in two different contexts.

"We use AI to draft the emails, personalised by the signal we collect on the customer. And it's the same practices we implement when writing our own emails. Sponja itself writes the sequences using AI, and it's the same principles we use ourselves."

When a founder builds outreach the way he builds software, from first principles, with a clear theory about why something works, the results tend to look different from everyone else's.

Support That Escalated Honestly and Resolved Fast

Roee's support experience has no dramatic moments. The Smart Assistant handled the vast majority of questions in real time. The one or two times it encountered something beyond its scope, it handed off cleanly to a human.

"Once or twice there was a bug, so the assistant couldn't help me, so it redirected me to human support. The response wasn't instant because it wasn't AI, but relative to other businesses and service providers, it was quite fast. Right on point."

A support system that knows its own limits and escalates without friction is exactly what a solo founder running infrastructure needs. No unresolved tickets. No problems that compounded into campaign failures. Just a platform that worked and a team that showed up when it did not.

Ready to Replicate These Results

You can replicate these results when you treat cold outreach as a system rather than a guessing game.

Start by fixing deliverability with Smartlead's automated warm-up. Clean your data before every campaign. Build copy around signals your prospect actually recognises, not template fields they have seen a hundred times before.

The difference between a 5% reply rate and a 50% reply rate is not a better subject line. It is tighter list quality, infrastructure that keeps emails in the primary inbox, and personalisation that starts from something real.

Ready to build your own outbound engine? Start your free trial on Smartlead and use the same infrastructure Roee used to win Sponja's first paying customer. Track every metric, tighten every variable, and watch the results compound. Review the complete Smartlead pricing breakdown to see how the model scales as your outreach grows.

For more on building a cold email system that delivers, read the email deliverability guide or explore how AI is changing cold email outreach before your next campaign launch.

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