Piotr Mikrut is the founder of Experiment5M, a customer acquisition agency specializing in cold outreach through email, LinkedIn, and personal branding. Serving B2B clients including marketing agencies, software companies, and SaaS businesses primarily across Europe and the US, Experiment 5M delivers personalized contact databases, strategic outreach, and full campaign management.
Piotr’s cold email journey started as a cost-effective growth channel when launching Greencrm, a solar industry-focused CRM company. He quickly realized the power of cold outreach and transitioned into agency work, helping clients generate substantial growth via outbound email.
Initially, Piotr used various outreach tools but faced major hurdles:
Connecting large numbers of mailboxes and managing multi-campaign data transfers were time-consuming and error-prone.
Managing bounced contacts and do-not-contact lists was difficult, causing frustration when contacts received unwanted follow-ups.
Lack of strong API integrations restricted campaign automation, leading to inefficient workflows.
Clients struggled to view and respond to campaign replies efficiently without direct access to platforms.
Piotr needed a scalable, reliable solution with powerful automation and deliverability features to support his growing client base.
After researching and testing a few platforms in the cold email domain, Piotr chose Smartlead for its unique strengths:
Enabled seamless automation by integrating campaign launches and response handling directly with Clay and other tools.
Allowed connecting hundreds of mailboxes quickly, reducing campaign setup time from hours to minutes. Also, the master inbox is an quick and efficient way to manage all replies in a single place.
Provided client portals where clients could securely log in and engage with their campaign data.
Offered clear previews of spintax variations, ensuring high-quality, unique messaging.
Enabled replies directly from the sending email account within Smartlead, improving client responsiveness.
Comprehensive inbox warm-up and spam protection tools kept campaigns healthy.
Piotr appreciates that Smartlead is widely adopted in his professional community, enhancing collaboration and support.
Experiment5M integrated Smartlead tightly into their outbound strategy:
Notably, the automation and bulk mailbox connection saved the team countless hours monthly, allowing more focus on campaign strategy and client success.
Piotr shared some things he would like to see from Smartlead in the future:
Piotr believes Smartlead’s rapid feature development and open feedback culture help mitigate issues over time.
Piotr Mikrut’s experience with Smartlead highlights the power of automation and deliverability-centric platforms in scaling cold outreach agencies. By integrating Smartlead’s API-driven tools and client portals, Experiment5M has streamlined campaign management, improved client transparency, and significantly cut manual workload.
“Smartlead’s automation and deliverability features transformed how we run outbound campaigns. The API integrations and client portals gave us the scalability and transparency we needed. While there’s room for growth, this platform has been a game changer for our agency.” – Piotr Mikrut, Founder, Experiment5M
This case study demonstrates how a robust email outreach platform can empower agencies to automate at scale, drive engagement, and build trusted client relationships — all critical factors for success in today’s competitive cold email landscape.
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Founder, StackOptimise
Smartlead's combination of automation, unlimited inboxes, and easy campaign management has completely transformed how we run cold email campaigns.
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Founder, Cold Email Hackers
We have about 15 companies and we use Smartlead for all of them.
Founder, DutchSave Media
One of the things I love about using Smartlead is the deliverability feature. If they landed in the bounce or spam folders, we could resolve this quickly.
Co-Founder, Growth Today
I want to continue to use Smartlead to make operations more seamless - the plan is to bring more clients here and build more SOPs.
Founder, FueltoFly
Smartlead listens to the agencies and customers and builds according to what people want, that has really made things easier for us.
Founder, OutboundSync
We build an infrastructure product, and OutboundSync communicates with Smartlead itself. I love the webhook and API. They're really well done and keep getting better.
Founder, Axoleads
With SmartDelivery, you can put all of that in the hands of the tool. It ensures your emails land in inboxes, and by running a simple test, you can see if you're hitting the mark.
Founder, Claygen
Deliverability is the cornerstone of cold email outreach. You could have the best email copy in the world, but if no one is seeing it, it's useless. I really love the feature where you can actually give client accesses to your clients.
Co-Founder, Cymate
I do not want to switch to another software. Pick a solution you trust, stick with it, and keep refining your copy.
CMO, Avalanche Capital
Managing large volumes of emails through multiple inboxes used to be a logistical nightmare. With Smartlead, the process is seamless. We book thousands of discovery calls through cold emails. These campaigns are generating leads at a scale we never thought possible.
Founder, Growth Engine X
We came for the unlimited inboxes, and we stayed for the API. 1.5M cold emails/month, 7,767+ inboxes managed.
Head of Community & Ecosystem, TxtCart
You cannot replace having 10,000 touches with potential clients. When you have that much distribution and reach, you really start to see incredible results. The simplicity of Smartlead made all the difference. It doesn't require you to be a technical wizard.
Founder, Hyperke
Smartlead has been a game-changer for us. It increased our appointment volume, improved ease of use, and offered valuable features. 80% increase in appointments/month, peak of 276 appointments in a single month.
Founder, Kinetyca
Smartlead has been our cold email backbone from day one. The platform evolves constantly, keeping pace with how deliverability and personalization need to work today. 21% overall reply rate, $175K in 4 months for multiple B2B clients.
Founder, Reachflow
Smartlead is centered around deliverability and constantly evolving. Their API is not like any other platform. Smartlead covers all our needs. The focus on core features like deliverability and API integration is unmatched.
CEO, Halfwarm
Our approach to crafting conversational emails led to reply rates that many of my peers thought were unattainable.
Co-Founder, letstrike
We've grown on zero capital, zero marketing, purely cold emailing - and that's the story we love to tell. The best approach is no approach if you can't handle domain meltdown. The second best is something like Smartlead that's built from the ground up for deliverability at scale.
Founder, Fenixtal
Smartlead's white-labeling and automation let us punch above our weight. The 12M euros sales potential? That's what happens when you combine human creativity with Smartlead's precision.
Co-Founder, Digital Creativs
Nine out of 10. Ninety percent of our clients are on Smartlead unless they come in with an existing setup. That's the default.
Co-Founder, BuildingReach
At the end of the day, you have to take a bet on one tool or another. It was a no-brainer taking that bet on Smartlead. We had to even turn down the volume of our marketing campaigns - Smartlead was capable of driving more volume than our sales team was able to fulfill.
Founder & MD, Prospectiv
Since starting the business in January of this year, we've already generated $200K in sales exclusively from cold email. Smartlead has been central to our operations and has exceeded our expectations.
Founder, Growthlynk
There's so much stuff built on top of it. I would be dead if I had to rebuild it with another tool. I can manage hundreds of senders easily. I can send hundreds of thousands of emails.
Founder, Corebits
The platform's HubSpot integration, real-time Slack updates, and advanced campaign customization have been game changers for our business and our clients'.
Founder, Apex Ascension
From day one, we've never used anything else.
