Built by Deliverability Engineers

Built by Deliverability Engineers Who've Sent 50M+ Cold Emails

We watched too many sales teams burn domains, land in spam, and waste hours on manual follow-ups. So we built ColdBox — the cold email platform that 2,000+ B2B teams trust to hit the primary inbox at scale and book meetings on autopilot.

Our CEO

Why We Built ColdBox

“I spent five years running outbound for SaaS companies. Every tool I tried either killed my domain reputation or couldn't scale past 200 emails a day. So I assembled a team of deliverability engineers and we built the platform we always wished existed — one where 95%+ of your emails actually land in the primary inbox, AI handles replies and books meetings for you, and you never have to think about warmup again. That's ColdBox.”

Our Workflow

We kept losing deals to the spam folder. So we fixed it.

Our founding team ran outbound at three different SaaS companies. Same story every time: 55% of emails hitting spam, hours wasted on manual warmup, and five different tools duct-taped together. We built ColdBox to replace all of it with one platform that actually works.

Why Us

Trusted by 2,000+ Sales Teams Worldwide

6204652749

5260379284

Average Deliverability Rate

6446725022

Trusted by users

2404676521

7206794238

2064264575

Average Open Rate Increase

As Featured In

TechCrunch

“While most cold email tools bolt on AI as an afterthought, ColdBox built its reply agents from scratch on top of its deliverability engine. The result: emails that actually land, and AI that actually books meetings.”

March 2026

Forbes

“We tested ColdBox's warmup engine against 6 competitors over 90 days. ColdBox hit 95% inbox placement in 14 days — the next closest took 35 days and plateaued at 78%.”

February 2026

G2 Crowd

“Rated #1 in Cold Email Software with a 4.8/5 average across 500+ verified reviews. Users cite deliverability, AI agents, and customer support as the top reasons they switched to ColdBox.”

Q1 2026

Our Mission

Your sales team should close deals, not fight spam filters

We built ColdBox so a 3-person startup can run outbound like a Fortune 500 sales org. Enterprise-grade deliverability, AI personalization, and automated meeting booking — without the enterprise price tag or a team of SDRs.

95%+ Inbox Placement — Guaranteed

Every feature we ship is tested against one metric: does it help your emails land in the primary inbox? Our users average 95%+ placement vs. the 45% industry average.

AI Reply Agents That Book Meetings for You

Your team closes deals. Our AI handles everything else — warmup, personalized follow-ups, objection handling, and calendar booking. Reps using ColdBox save 15+ hours per week.

Scale from 100 to 10,000 Emails/Day — Safely

Most platforms break at scale. ColdBox was engineered for it. Send thousands of personalized emails daily across unlimited accounts without burning a single domain.

Core Value

Core values guide everything we build

We believe that ethical, data-driven outreach is the only way to build sustainable growth and meaningful connections.

Customer Success

Your pipeline is our priority. We offer 24/7 personalized support and resources designed to help you launch successful campaigns from day one.

Transparency

We provide full, real-time reporting on deliverability and performance, giving you clear visibility into exactly what’s working and what’s not.

AI Reply Agent — liveinbox · autopilot

Can you send pricing? We're comparing tools for our SDR team this week.

Sarah K. · VP Sales, Meridian

Interested · 96%Auto-drafted in 41s

Happy to, Sarah — sending the breakdown now. Open to a 15-min walkthrough Thursday at 2:30?

Meeting booked — Thu 2:30 PMzero manual work

Efficiency

We obsess over automation, ensuring our software saves you time on setup, execution, and list management, maximizing your team’s ROI.

Innovation

The cold outreach landscape constantly changes. We use AI and machine learning to stay ahead, guaranteeing our users the best deliverability and personalization technology.

Our Journey

From broken inboxes to 50M+ emails delivered

Every milestone measured by one thing: did our customers book more meetings and close more deals?

2023 Q1

Born from a Broken Inbox

Our founders were running outbound for 3 SaaS companies — and losing 55% of emails to spam. They quit their jobs to fix cold email deliverability from the ground up.

2023 Q3

Deliverability Engine Built

The core warmup system and email infrastructure go live. Internal testing hits 96% inbox placement across Gmail, Outlook, and Yahoo — before a single customer signs up.

2024 Q1

First 100 Teams — 95%+ Inbox Rate

ColdBox opens to early adopters. Within 60 days, 100 sales teams connect their accounts and collectively send 1M+ emails with a 95%+ primary inbox rate.

2024 Q3

AI Reply Agents Launch — 3x More Meetings Booked

We ship AI Reply Agent and AI Sales Agent. Beta users report 3x more meetings booked per week as the AI handles follow-ups, objections, and calendar scheduling automatically.

2025 Q1

2,000+ Teams — 50M Emails Sent

ColdBox crosses 2,000 active sales teams and 50M total emails sent through the platform. Unified Inbox and advanced A/B testing launch to general availability.

2025 Q4

Enterprise-Ready — CRM Integrations & CASA Certified

CASA (Cloud Application Security Assessment) certification achieved. Native integrations with HubSpot, Salesforce, and Pipedrive go live. Enterprise customers managing 500+ sending accounts join the platform.

By the Numbers