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For developers & agencies

The Cold Inbox API

Create, manage, and scale SMTP inboxes programmatically. Unlimited domains, 100 inboxes, starting at $25/month

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What You Get

Core Features

✅Unlimited domains (create as many as you need)
✅100 inboxes included (30MB each, 3GB total)
✅Unlimited receiving (no operation limits)
✅Full API access (create, manage, delete inboxes)
✅SMTP credentials (email + password for each inbox)
✅Domain management (add your own domains)
✅Automated DNS configuration (SPF, DKIM, DMARC setup handled automatically)

Technical Capabilities

• REST API for inbox creation/management
• Standard SMTP output (works with any email platform)
• Real-time inbox activation
• Domain verification handling

What You'll Need Separately

Email Warmup (Required)

Why: SMTP inboxes need reputation building for optimal deliverability

Options: Smartlead, Lemwarm, MailReach, or ColdSend's upcoming warmup

Timeline: 2-3 weeks for optimal results

Lead Generation (Optional)

Options: FindyMail, Apollo.io, AnyMail Finder

Why: We focus on infrastructure, not lead databases

Pricing

Base Package: $25/month

✅Unlimited domains
✅100 inboxes included (30MB each)
✅Receiving only (unlimited)
✅Full API access
✅SMTP credentials

Add-Ons:

Additional Inboxes: $10 per 50 inboxes (1.5GB storage)

Sending Credits: $10 per 10,000 emails (works across all inboxes)

Example Pricing

Use Case	Base Plan	Extra Inboxes	Sending Credits	Monthly Total
Receiving Only	$25	$0	$0	$25
Small Agency	$25	$10 (50 more)	$10 (10K emails)	$45
Growing Business	$25	$20 (100 more)	$20 (20K emails)	$65
Large Operation	$25	$40 (200 more)	$50 (50K emails)	$115

🏆 Competitive Edge

Competitive Advantage

vs. MailSlurp

MailSlurp Starter: $42/month for 1,000 inboxes + 1 domain + 1,000 emails

ColdSend Equivalent: $35/month for 100 inboxes + unlimited domains + 10,000 emails

Your advantages: Unlimited domains, more emails included, lower cost

vs. Traditional Infrastructure

Others: $2-4 per inbox + domain costs + complex setup

ColdSend: Simple base plan + clear add-on pricing + unlimited domains

🎯 Target Audience

Perfect For

Lead generation agencies needing multiple domains

SaaS companies scaling programmatically

Developers building email automation

Apollo scrapers and data enrichment workflows

Anyone needing SMTP infrastructure at scale

Technical Integration

API Documentation: coldinboxapi.coldsend.pro
Supported Platforms: Any tool accepting SMTP credentials
Popular Integrations: Smartlead, Instantly, Apollo, custom scripts
Webhook Support: Real-time notifications for inbox events

Getting Started

Sign up for base package ($25/month)
Create domains via API or dashboard
Configure DNS with provided values (we calculate, you add)
Generate inboxes programmatically
Get SMTP credentials for each inbox
Add sending credits when ready to send
Integrate with warmup tools for optimal deliverability

Ready to Scale Your Email Infrastructure?

Questions? Let's schedule a quick demo to show you the API in action and discuss your specific use case.