Case Study

Calvin Wiltermood on Scaling with Smartlead: Closed $700K+ ARR for His Agency

Wajahat Ali
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February 24, 2026
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Key Highlights

  • Closed +$700K ARR for their business in competitive spaces
  • 33% Positive Reply Rate for a 13,000 prospects campaign
  • 5x efficiency with cold emailing

About Calvin Wiltermood

With a strong background in B2B lead generation and a huge passion to help founders bet on themselves, Calvin Wiltermood’s career began in sales, where he worked his way from a Business Development Representative (BDR) to a Team Lead and eventually an Enterprise Account Executive.

After working with several companies, including a SaaS company, Calvin joined as an Advisor for Trailway Growth, focusing on automated cold email outreach for B2B clients. 

Calvin’s deep understanding of cold emailing and his hands-on experience with different tools in the market have enabled his agency to scale its outbound processes effectively, reaching clients in diverse industries like SaaS, Tech, and Marketing.

The Challenge

Calvin Wiltermood specializes in helping technical founders (solopreneurs → public companies) build revenue engines. Traditional cold calling was effective but unscalable:

"If I wanted to book a meeting, I needed to spend X hours on the phone. Our clients are accountants, lawyers, salespeople – all in one. They needed something automated."

Before discovering Smartlead, Calvin tried almost every tool in the market but faced several challenges that hindered his ability to scale cold email outreach effectively. Some major challenges included:

Deliverability Issues

Previously used didn’t offer good deliverability and lead to Inbox burnout and monthly deliverability crises.

Inbox Crashing

No agility to pivot during ESP outages (e.g., Outlook inboxing crashes).

Inefficient Client Campaign Management

No unified view and managing 50+ clients with different campaigns and ensuring all inboxes were operating smoothly became increasingly difficult.

Manual Reply Categorization

Without proper tools to manage and categorize replies automatically, Calvin and his team spent too much time on manual tasks.

Why Smartlead?

After testing various cold email tools, Calvin turned to Smartlead for its superior deliverability features, robust API integration, and automation capabilities

He was introduced to Smartlead through recommendations from peers in the industry, and after using the platform for a year and a half, he found that it perfectly addressed the needs of his agency.

Key Reasons for Choosing Smartlead:

Multi-Inbox Management at Scale:

  • Managed 45,000+ inboxes with instant adjustments during deliverability fires.

Deliverability Safeguards:

  • Warming pools with real-time tracking and DNS record checks preempted issues.
  • Critical during crises (e.g., October Outlook collapse), where Smartlead’s analytics provided client-facing transparency.

Automation Flexibility:

  • Webhooks enabled custom reply-management sequences and CRM syncs.
“We’re barely scratching the surface of what’s possible. It’s a foundation for agency growth.”

Client-Centric Analytics:

  • Filtered performance data by client/seat to optimize campaigns individually.
“Smartlead, without a doubt, in my opinion, is the best tool in the market for cold email outreach”.

Solutions Offered by Smartlead

Massive Inbox Scalability

  • Managed 45,000+ inboxes with centralized control.
  • Enabled instant swaps during deliverability crises (e.g., burned inboxes, ESP outages).
*"When inboxes burned, we fixed it in minutes which was crucial as we were handling this for our 35+ clients."*

Proactive Deliverability Safeguards

  • Real-time warming pools to maintain sender reputation.
  • DNS record diagnostics to preempt configuration errors.
  • Critical during ESP collapses (e.g., Smartlead’s Outlook inboxing data helped pivot strategies mid-crisis).

Automation via Webhooks & API

Client-Specific Analytics

  • Filtered performance data per client/seat (e.g., reply rates, positive responses).
  • Enabled granular optimizations for diverse campaigns (SaaS vs. blue-collar niches).

Security & Workflow Hygiene

  • Restricted inbox deletion to prevent infrastructure sabotage.
  • Clear-formatting tool to eliminate email template errors from pasted text.

Results Achieved

After using Smartlead, Calvin experienced remarkable improvements in their cold email campaigns, delivering outstanding results for their clients:

  • 33% Positive Reply Rate in a high-volume campaign (13,000 prospects).
  • 5x Efficiency vs. Cold Calling with scalable outreach without proportional labor.
  • Used Smartlead’s inboxing data to advise clients during ESP outages, building trust.
  • More than $700K Closed in ARR for their business in competitive spaces (SaaS, FinTech) and underserved niches.

Why Smartlead Stands Out

Beyond features, Calvin highlights:

Founder-Led Community

Webinars with industry leaders and Slack networking are a major plus point with Smartlead.

Security-First Approach

Restricted inbox deletion prevented catastrophic errors.

Clear Formatting Tools

Clear formatting seems small, but saved them from endless formatting disasters.

Looking Ahead

Trailway continues to leverage Smartlead for its 35+ client roster. Calvin’s wishlist?

  • Bulk inbox management requests.
  • Extended analytics beyond 30-day windows.
  • Daily reply-rate tracking for faster deliverability insights.
“No matter what, I’ll always ask for more data – but Smartlead remains the best in the market.”

Conclusion

By providing robust tools for email deliverability, API integration, and client management, Smartlead has allowed Calvin and his team to scale their outbound efforts, automate follow-ups, and consistently achieve impressive results for clients.

Smartlead empowers agencies and lean teams to scale email outreach with enterprise-grade deliverability.

For agencies looking to scale their outbound efforts, Smartlead provides the tools and infrastructure to succeed. Their 14-day free trial is a good way to start testing the tool for your agency.

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Wajahat Ali

Wajahat Ali is a Technical Content Writer at Smartlead, specializing in the B2B and SaaS sectors. With a talent for simplifying complex concepts, he crafts clear, engaging content that makes intricate topics accessible to both experts and newcomers. Wajahat’s expertise spans across copywriting, social media content, and lead generation, where he consistently delivers valuable, impactful content that resonates with a global audience. His ability to blend technical knowledge with compelling storytelling ensures that every piece of content drives both understanding and results, helping businesses connect with their target markets effectively.

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What our customers say

Bojan Najdov

Founder, Lambda Group

“The best outbound email marketing software. Customer support - they are so responsive and helpful Features - you can add multiple email doma”

David Borman

Senior Account Executive, Key Outreach

"Intuitive. Game-Changing. POWERFUL. Analytics, spintax, A/B testing, quick personalization. This is a game changer if you send cold email ca"

Eden Einav

Account Executive, B.I.G. Charity Law Group Professional Corporation

“Hands down the best cold email software. Smartlead is amazing, this is the best tool if you want to cold email at scale and land in the inbo”

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Co-founder, Pitchlane

“Innovative, reliable, and Suitable For Technical and Non-Technical Users. SmartLead's ability to help me land in the primary inbox and autom”

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Co-Founder, Five Element

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Sales Director - Financial Institution Solutions Saggezza, Inc.

“Smartlead is an innovative cold email platform that helps me reach out to potential clients. There are easy-to-use templates, powerful autom”

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“I've personally built a sales engagement platform similar to Smartlead, and I am genuinely blown away by the scalability, functionality and”

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"I can upload hundreds of email accounts, send thousands of cold emails per day, and still have an organized master inbox. This is unseen wit"

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“Smartlead has been extremely helpful with seamlessly onboarding clients, warming up their accounts, and prepping campaigns to send at high v”

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“Smartlead is absolutely amazing! The software is easy to understand I am not a techie but directly understand everything and if you really h”

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Founder, WindGrowth

“Smartlead is simply amazing. They constantly improve their product and bring new features that make the cold email software even more comple”

Lucas Maliczak

Outbound Lead & Partner, Peakora

“Our campaigns weren't just about reaching out, but reaching out right, and Smartlead helped us achieve this. It has added immense value to o”

Romain Osman

Co-Founder, Five Element

“Smartlead is an absolute game-changer! With its exceptional features and support from the Smartlead team, I've experienced remarkable succes”

Arnold Koci

CEO, Acquisizioneclienti.it

“Best cold outbound email software out there. Everything, is fast, reliable, scalable, you can also white-label, amazing analytics and never”

Cliff Coelho

Owner, Storydriven.video

“I just ended my 2 year search for the right cold emailing platform with Smartlead. A stand alone tool for cold emailing unlike anything else”

David Borman

Senior Account Executive, Key Outreach

“Intuitive. Game-Changing. POWERFUL. Analytics, spintax, A/B testing, quick personalization. This is a game changer if you send cold email campaign. Grateful to this team for building a product that has changed our day to day. 🚀”

Powerful automated workflows that drive sales.

Try Smartlead's AI-led outbound system today.

Frequently asked questions

What is Smartlead's cold email outreach software?
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Smartlead's cold email outreach tool helps businesses scale their outreach efforts seamlessly. With unlimited mailboxes, fully automated email warmup functionality, a multi-channel infrastructure, and a user-friendly unibox, it empowers users to manage their entire revenue cycle in one place. Whether you're looking to streamline cold email campaigns with automated email warmups, personalization fields, automated mailbox rotation, easy integrations, and spintax, improve productivity, or enhance scalability with subsequences based on lead’s intentions, automated replies, and full white-label experience, our cold email tool implifies it in a single solution.

How does Smartlead's unlimited mailboxes feature benefit me?
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Our "unlimited mailboxes" feature allows you to expand your email communications without restrictions imposed by a mailbox limit. This means you won't be constrained by artificial caps on the number of mailboxes you can connect and use. This feature makes Smartlead the best cold email software and empowers you to reach a wider audience, engage with more potential customers, and manage diverse email campaigns effectively.

What do you mean by "unibox to handle your entire revenue cycle"?
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The "unibox" is one of the unique features of Smartlead cold email outreach tool, and it's a game-changer when it comes to managing your revenue cycle. The master inbox or the unibox consolidates all your outreach channels, responses, sales follow-ups, and conversions into one centralized, user-friendly mailbox.

With the "unibox," you gain the ability to:
1. Focus on closing deals: You can now say goodbye to the hassle of logging into multiple mailboxes to search for replies. The "unibox" streamlines your sales communication, allowing you to focus on what matters most—closing deals.

2. Centralized lead management: All your leads are managed from one central location, simplifying lead tracking and response management. This ensures you take advantage of every opportunity and efficiently engage with your prospects.

3. Maintain context: The "unibox" provides a 360-degree view of all your customer messages, allowing you to maintain context and deliver more personalized and effective responses.

Can Smartlead help improve my email deliverability rates?
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Yes, our cold emailing software is designed to significantly improve your email deliverability rates. It enhances email deliverability through AI-powered email warmups across providers, unique IP rotating for each campaign, and dynamic ESP matching.

Real-time AI learning refines strategies based on performance, optimizing deliverability without manual adjustments. Smartlead's advanced features and strategies are designed to improve email deliverability rates, making it a robust choice for enhancing cold email campaign success.

Can I integrate Smartlead with other tools I'm using?
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Certainly, Smartlead cold email tool is designed for seamless integration with a wide range of tools and platforms. Smartlead offers integration with HubSpot, Salesforce, Pipedrive, Clay, Listkit, and more. You can leverage webhooks and APIs to integrate the tools you use. Try Now!

What is Smartlead, and how can it enhance my cold email campaigns?
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Smartlead is a robust cold emailing software designed to transform cold emails into reliable revenue streams. Trusted by over 31,000 businesses, Smartlead excels in email deliverability, lead generation, cold email automation, and sales outreach. A unified master inbox streamlines communication management, while built-in email verification reduces bounce rates.Additionally, Smartlead offers essential tools such as CNAME, SPF Checker, DMARC Checker, Email Verifier, Blacklist Check Tool, and Email Bounce Rate Calculator for optimizing email performance.

How does Smartlead, as a cold emailing tool, automate the cold email process?
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Smartlead’s robust cold email API and automation infrastructure streamline outbound communication by transforming the campaign creation and management processes. It seamlessly integrates data across software systems using APIs and webhooks, adjusts settings, and leverages AI for personalised content.

The cold emailing tool categorises lead intent, offers comprehensive email management with automated notifications, and integrates smoothly with CRMs like Zapier, Make, N8N, HubSpot, Salesforce, and Pipedrive. Smartlead supports scalable outreach by rapidly adding mailboxes and drip-feeding leads into active campaigns Sign Up Now!

How does Smartlead ensure my emails don't land in the spam folder?
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Smartlead, the best cold email marketing tool, ensures your emails reach the intended recipients' primary inbox rather than the spam folder.

Here's how it works:
1. Our "unlimited warmups" feature is designed to build and maintain a healthy sending reputation for your cold email outreach. Instead of sending a large volume of emails all at once, which can trigger spam filters, we gradually ramp up your sending volume. This gradual approach, combined with positive email interactions, helps boost your email deliverability rates.

2. We deploy high-deliverability IP servers specific to each campaign.

3. The ‘Warmup’ feature replicates humanized email sending patterns, spintax, and smart replies.

4. By establishing a positive sender reputation and gradually increasing the number of sent emails, Smartlead minimizes the risk of your emails being flagged as spam. This way, you can be confident that your messages will consistently land in the primary inbox, increasing the likelihood of engagement and successful communication with your recipients.

What features does Smartlead offer for cold email personalisation?
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Smartlead enhances cold email personalisation through advanced AI-driven capabilities and strategic integrations. Partnered with Clay, The cold remaining software facilitates efficient lead list building, enrichment from over 50 data providers, and real-time scraping for precise targeting. Hyper-personalised cold emails crafted in Clay seamlessly integrate with Smartlead campaigns.

Moreover, Smartlead employs humanised, natural email interactions and smart replies to boost engagement and response rates. Additionally, the SmartAI Bot creates persona-specific, high-converting sales copy. Also you can create persona-specific, high-converting sales copy using SmartAI Bot. You can train the AI bot to achieve 100% categorisation accuracy, optimising engagement and conversion rates.

Is Smartlead suitable for both small businesses and large enterprises?
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Smartlead accommodates both small businesses and large enterprises with flexible pricing and comprehensive features. The Basic Plan at $39/month suits small businesses and solopreneurs, offering 2000 active leads and 6000 monthly emails, alongside essential tools like unlimited email warm-up and detailed analytics.

Marketers and growing businesses benefit from the Pro Plan ($94/month), with 30000 active leads and 150000 monthly emails, plus a custom CRM and active support. Lead generation agencies and large enterprises can opt for the Custom Plan ($174/month), providing up to 12 million active lead credits and 60 million emails, with advanced CRM integration and customisation options.