6 Best Cold Email Agencies for B2B Lead Gen

Cold email agencies help B2B companies generate leads and book meetings without building internal SDR teams. These agencies range from email-only specialists to full omnichannel operations combining phone, LinkedIn, and email. The right choice depends on your budget, sales cycle complexity, and how much involvement you want in the process.

We built Outbound System around a simple principle: cold email should be 100% done for you, so all you have to do is close the deal. But we're not the right fit for everyone. This guide compares the top cold email agencies so you can find the best match for your situation.

Short Answer: Outbound System handles pure done-for-you cold email without SDR overhead. Belkins and CIENCE offer enterprise omnichannel campaigns. SalesRoads specializes in phone-first outbound. Martal Group provides global reach. Leadium offers boutique US-based service.

Table of Contents

1. Outbound System

2. Belkins

3. CIENCE

4. SalesRoads

5. Martal Group

6. Leadium

7. Agency Comparison Summary

8. Frequently Asked Questions

1. Outbound System

Positioning: Cold email 100% done for you—all you have to do is close the deal.

Outbound System is a B2B cold email agency that runs outbound entirely on your behalf. We handle domain setup, email warmup, list building, copywriting, sending at scale, and reply management by default. The model is designed for teams that want meetings without managing any outreach infrastructure themselves.

Our process starts with a kickoff call to define your ICP, followed by real-time list building using premium B2B databases. We set up fresh domains with proper DKIM, DMARC, and SPF authentication, warm them for two weeks, then launch personalized outreach. You can choose whether we handle replies or pass warm leads directly to your team.

Best for:

• B2B SaaS companies wanting outbound without hiring SDRs

• Agencies selling services to other businesses

• Professional services firms (consultants, accountants, lawyers)

• Teams that want zero involvement in outreach mechanics

• Companies prioritizing email-only outreach over multichannel complexity

When to consider alternatives:

• Enterprise companies needing phone + email + LinkedIn orchestration

• Teams wanting to run outreach in-house with agency guidance

• Companies requiring dedicated SDRs assigned to their account

2. Belkins

Positioning: Award-winning B2B appointment setting combining email, calling, and LinkedIn at enterprise scale.

Belkins is one of the larger B2B lead generation agencies, offering omnichannel appointment setting across email, cold calling, and LinkedIn. They've tested over 50,000 email variations across 50+ industries and emphasize hand-verified lead research against buyer personas. Their typical email cadence runs 4-5 touches with outcome-focused, spam-word-free messaging.

Campaigns launch in about 14 days with results typically appearing within 30-90 days. Belkins also offers deliverability consulting, HubSpot CRM consultancy, and sales enablement services—making them a fit for companies wanting a comprehensive revenue partner rather than just email execution.

Best for:

• Mid-market to enterprise B2B companies

• Teams needing omnichannel orchestration (email + phone + LinkedIn)

• Companies wanting strategic consulting alongside execution

• Organizations with longer, complex sales cycles

Belkins vs Outbound System

Belkins and Outbound System take fundamentally different approaches. Belkins is a full-service omnichannel agency—they combine email, phone, and LinkedIn into coordinated campaigns with dedicated SDRs. Outbound System focuses exclusively on cold email, handling everything from domains to replies without the complexity of multiple channels.

Belkins is the better choice when your sales cycle requires multiple touchpoints, when phone conversations significantly improve conversion, or when you need strategic consulting beyond just execution. Pricing typically runs $5,000-$15,000/month, reflecting the broader scope.

Outbound System is the better choice when email alone can drive your pipeline, when you want simpler execution without managing SDRs, or when you prefer a more focused, streamlined engagement. The email-only approach means faster setup and less coordination overhead.

3. CIENCE

Positioning: AI-powered GTM platform combined with managed SDR services for scalable multi-channel outbound.

CIENCE operates as both an SDR agency and a technology platform (graph8). They run large, multi-channel campaigns combining email, phone, chat, SMS, and ads—functioning more like outbound infrastructure than a boutique agency. Their model blends AI automation with human SDRs for prospect research, sequence crafting, and campaign management.

CIENCE's pricing includes a $5,000 one-time GTM system setup (or $2,500 for startups) plus ongoing monthly fees typically ranging $4,200-$9,000. They're built for companies that want predictable outbound systems running across multiple channels simultaneously, with deep CRM integration and proprietary data tools.

Best for:

• Mid-market to enterprise B2B tech and SaaS companies

• Organizations wanting AI-augmented outbound at scale

• Teams needing integrated data, outreach, and CRM systems

• Companies with budget for significant upfront investment

CIENCE vs Outbound System

CIENCE and Outbound System operate at different scales and with different philosophies. CIENCE is outbound infrastructure—a technology platform plus managed services that runs multi-channel campaigns across email, phone, chat, SMS, and even ads. Outbound System is focused execution—we do cold email extremely well without the complexity of a full GTM platform.

CIENCE is the better choice when you need enterprise-scale outbound across multiple channels, when you want AI-powered prospecting integrated with your CRM, or when you're building systematic pipeline generation across a large sales organization. The $5,000 setup fee and $4,000-$9,000/month reflects this enterprise scope.

Outbound System is the better choice when email is your primary channel, when you don't need the complexity of a full GTM platform, or when you want to start generating meetings without significant upfront investment. We focus on doing one thing—cold email—and doing it well.

4. SalesRoads

Positioning: 17+ years of US-based SDR expertise with phone-first outbound and AI-boosted email cadences.

SalesRoads is one of the most established US-based appointment setting agencies, with 17+ years of experience and 100K+ appointments set for growing companies. Their SDRs average 5-10 years of sales experience and are directly managed by dedicated sales coaches. The model combines structured cold calling with AI-enhanced email campaigns.

Their process starts with a two-hour deep dive into your business, distilled into a comprehensive sales playbook. Pricing starts around $9,500 for 4 weeks and includes a dedicated SDR, sales operations team, director of client success, and talent development manager. They recently acquired VSA Prospecting, expanding their capabilities.

Best for:

• Companies where phone conversations drive conversions

• US-focused B2B sales targeting decision-makers

• Teams wanting experienced, US-based SDRs

• HR software, SaaS, property tech, recruitment, marketing agencies

SalesRoads vs Outbound System

SalesRoads and Outbound System represent opposite ends of the outbound spectrum. SalesRoads is phone-first—their SDRs make calls as the primary channel, with email supporting the phone outreach. Outbound System is email-first (and email-only)—we believe cold email alone can fill your pipeline without adding phone complexity.

SalesRoads is the better choice when your prospects prefer phone conversations, when your sales cycle benefits from voice-to-voice qualification, or when you're targeting industries where phone outreach significantly outperforms email. Their experienced US-based SDRs (5-10 years average experience) are ideal for complex, consultative conversations. Pricing starts around $9,500/month.

Outbound System is the better choice when your prospects respond well to email, when you don't want to manage or coordinate with SDRs, or when you prefer the efficiency of email-only outreach. We handle everything without requiring phone infrastructure or managing callers.

5. Martal Group

Positioning: 200+ person global SDR team specializing in tech and SaaS with both North American and international reach.

Martal Group combines a large team of sales executives with AI-driven prospecting tools for B2B outbound across email, LinkedIn, and cold calling. They've executed lead generation in 50+ industries and emphasize intent data, buying signals, and continuous campaign optimization. Their international team provides coverage across multiple geographies.

Martal requires a 3-month pilot program before transitioning to month-to-month billing. Their model works well for companies needing consistent, informed outreach rather than experimental campaigns, particularly those with global target markets.

Best for:

• B2B tech companies targeting mid-market or enterprise accounts

• Organizations needing international outreach capabilities

• Teams wanting AI-augmented prospecting with human execution

• Companies willing to commit to a 3-month pilot

Martal Group vs Outbound System

Martal Group and Outbound System differ in scale, scope, and commitment structure. Martal operates with 200+ sales executives across multiple countries, running coordinated campaigns via email, LinkedIn, and phone. Outbound System focuses exclusively on cold email with a leaner, more specialized approach.

Martal is the better choice when you need international coverage, when your targets span multiple geographies, or when you want a large SDR team running multi-channel campaigns at scale. Their 3-month pilot requirement reflects the complexity of their setup. They specialize in tech and SaaS companies with mid-market to enterprise targets.

Outbound System is the better choice when your targets are primarily in one market, when email alone can drive your pipeline, or when you want flexibility without a 3-month commitment. We're focused on doing cold email exceptionally well rather than spreading across multiple channels and geographies.

6. Leadium

Positioning: Founder-led boutique agency with omnichannel outreach including email, phone, LinkedIn, SMS, and strategic gifting.

Leadium positions itself as a founder-led, 100% US-based sales agency focused on quality over volume. They run omnichannel appointment setting across email, cold calling (averaging 15% connect rates), LinkedIn, SMS, and even curated gifting campaigns. Their research team provides human-sourced and validated contact data with channel optimization recommendations.

Leadium operates on month-to-month contracts with projects starting from $1,000, making them accessible to smaller businesses while still serving enterprise clients. They emphasize transparency with shared Slack channels and real-time analytics access.

Best for:

• SaaS, cybersecurity, and tech companies

• Startups wanting enterprise-grade outbound at accessible pricing

• Teams valuing US-based SDRs and founder-level attention

• Companies interested in strategic gifting as part of outreach

Leadium vs Outbound System

Leadium and Outbound System are both boutique-style agencies, but with different channel strategies. Leadium runs omnichannel campaigns across email, phone, LinkedIn, SMS, and even physical gifting—they're a full SDR team with multiple touchpoints. Outbound System specializes in cold email only, without the coordination complexity of managing multiple channels.

Leadium is the better choice when you want a US-based SDR team, when your sales process benefits from phone plus email, or when creative approaches like strategic gifting could differentiate your outreach. Their founder-led approach and transparent communication (shared Slack channels) work well for companies wanting close collaboration.

Outbound System is the better choice when email alone drives results for your business, when you prefer less complexity than omnichannel orchestration, or when you want true done-for-you service without managing SDR relationships. We handle the entire email process end-to-end.

Agency Comparison Summary

Quick Answer: Choose Outbound System for pure done-for-you email. Choose Belkins or CIENCE for enterprise omnichannel. Choose SalesRoads for phone-first. Choose Cleverly for LinkedIn-first. Choose Martal for global reach. Choose Leadium for boutique US-based omnichannel.

Frequently Asked Questions

How much do cold email agencies typically cost?

Pricing varies widely based on service scope. Email-only agencies may charge $1,000-$5,000/month. Full-service omnichannel agencies with dedicated SDRs typically run $5,000-$15,000/month. Enterprise-level services with AI platforms and multiple channels can exceed $10,000/month plus setup fees. Some agencies offer pay-per-lead or pay-per-meeting models for more predictable costs.

How long before I see results from a cold email agency?

Most agencies require 2-4 weeks for setup, including domain warming, list building, and messaging approval. First meetings typically appear within 30-60 days after launch. Full campaign optimization and predictable results usually take 60-90 days. Agencies that promise immediate results may be cutting corners on deliverability, which can harm your domain reputation.

Should I choose email-only or omnichannel outreach?

Email-only works well for straightforward B2B sales where prospects respond to written communication. Omnichannel (email + phone + LinkedIn) typically produces better results for complex sales cycles, high-value deals, or when targeting executives who are difficult to reach via email alone. Email-only is also more affordable and simpler to manage.

What's the difference between "done-for-you" and SDR-as-a-Service?

Done-for-you agencies handle everything from list building to reply management—you just show up to meetings. SDR-as-a-Service provides dedicated sales development representatives who work as an extension of your team, often requiring more coordination and oversight. DFY is hands-off; SDRaaS involves more collaboration.

Will cold email damage my domain reputation?

Reputable agencies use separate domains for outreach (not your primary domain), proper warmup protocols, and authentication (SPF, DKIM, DMARC). They send at appropriate volumes with clean lists. Agencies that skip these steps or send from your main domain can damage deliverability. Always confirm that the agency uses separate infrastructure.

How do I know if leads are qualified?

Quality varies by agency. Ask about their qualification criteria, whether they hand-verify leads against your ICP, and how they handle responses. The best agencies define qualification standards during onboarding and only book meetings with prospects matching your criteria. Request sample lead reports or case studies showing lead-to-opportunity conversion rates.

About the Author

Bruce Merrill is the Co-Founder of Outbound System and Founder of Cleverly, where he has pioneered scalable cold outreach methodologies since 2016. His expertise in B2B lead generation has been featured in Forbes, and he has personally overseen campaigns that generated over $50 million in pipeline for clients. Bruce scaled Cleverly to $5 million in annual recurring revenue before co-founding Outbound System, which he grew to $4 million ARR within two years. He previously served as the outbound strategist for LeaseLock, driving the company past $10 million in revenue. His companies have served over 10,000 B2B clients across SaaS, professional services, and enterprise technology. Bruce is recognized for developing the "Buying Signal Framework" and deliverability protocols now used by leading cold email agencies, and he is now focused exclusively on done-for-you cold email at Outbound System.