Overview
You'll learn how to calculate exactly how many domains and inboxes you need based on your daily campaign email volume, and which Inframail plan fits your sending requirements.
Prerequisites
Understanding of your target daily or monthly campaign email volume
Knowledge of your cold email outreach goals
Understanding the formula
Email sending capacity on Inframail is calculated using a simple formula based on safe sending practices:
Safe sending limit per inbox
Each email inbox can send up to 50 emails per day. However, we recommend 40 emails per inbox per day for optimal deliverability and to avoid spam filters.
Pro tip: The 40-email recommendation includes both warmup emails and live outbound emails. When we say "total emails," this breakdown is typically 70% warmup emails and 30% campaign emails. For example, if each inbox is sending 40 total emails per day, 28 of those would be warmup emails and 12 would be campaign emails.
Recommended inboxes per domain
For safe deliverability, we recommend 3-5 email inboxes per domain. You can create up to 10 inboxes per domain, but staying within the 3-5 range helps maintain better sender reputation.
The calculation formula
Step 1: Calculate total inboxes needed
Total Inboxes = Daily Campaign Email Volume ÷ 12 campaign emails per inboxStep 2: Calculate domains needed
Total Domains = Total Inboxes ÷ 3 inboxes per domainRound up to the nearest whole number for both calculations.
Calculation examples
Example 1: Sending 2,500 campaign emails per day
Calculate inboxes: 2,500 ÷ 12 = 208.3 inboxes (round up to 209)
Calculate domains: 209 ÷ 3 = 69.7 domains (round up to 70)
Daily capacity verification: 70 domains × 3 inboxes × 12 campaign emails = 2,520 campaign emails/day ✓
Remember: If you're sending 40 emails per day from each inbox, 70% is for warmup and 30% is for campaign emails. So 12 campaign emails out of the 40 total.
Result: You need 70 domains with 3 inboxes each (210 total inboxes) to safely send 2,500 campaign emails per day.
Example 2: Sending 5,000 campaign emails per day
Calculate inboxes: 5,000 ÷ 12 = 416.7 inboxes (round up to 417)
Calculate domains: 417 ÷ 3 = 139 domains
Daily capacity verification: 139 domains × 3 inboxes × 12 campaign emails = 5,004 campaign emails/day ✓
Remember: If you're sending 40 emails per day from each inbox, 70% is for warmup and 30% is for campaign emails. So 12 campaign emails out of the 40 total.
Result: You need 139 domains with 3 inboxes each (417 total inboxes) to safely send 5,000 campaign emails per day.
Example 3: Sending 10,000 campaign emails per day
Calculate inboxes: 10,000 ÷ 12 = 833.3 inboxes (round up to 834)
Calculate domains: 834 ÷ 3 = 278 domains
Daily capacity verification: 278 domains × 3 inboxes × 12 campaign emails = 10,008 campaign emails/day ✓
Remember: If you're sending 40 emails per day from each inbox, 70% is for warmup and 30% is for campaign emails. So 12 campaign emails out of the 40 total.
Important: With 834 inboxes, you'll need multiple dedicated IPs to distribute your sending infrastructure safely. The Agency Pack (3 IPs) is strongly recommended for this volume.
Choosing the right Inframail plan
Inframail offers two main subscription plans based on your sending volume and infrastructure needs:
Unlimited Plan - $99/month
Best for: Small agencies and businesses (∼50+ meetings/month)
What's included:
1 Dedicated IP ready-to-go
Unlimited Email Inboxes
5 Domain setups per day
FREE automation to setup emails
1-on-1 Deliverability Consultant
Priority Support
API Access
Agency Pack - $249/month
Best for: Growing agencies and high-volume senders (∼200+ meetings/month)
What's included:
3 Dedicated IPs ready-to-go
Unlimited Email Inboxes
15 Domain setups per day
FREE automation to setup emails
1-on-1 Deliverability Consultant
Priority Support
API Access
Annual plans (20% discount)
Both plans are available with annual billing at a 20% discount:
Annual Unlimited: $79.20/month (billed annually) + 70 FREE domain migrations
Annual Agency Pack: $199.20/month (billed annually) + 100 FREE domain migrations
Quick reference: General guideline for volume to plan mapping
Daily Campaign Email Volume | Inboxes Needed | Domains Needed | Recommended Plan |
|---|---|---|---|
1,000-2,000 | 84-167 | 28-56 | Unlimited Plan ($99/mo) |
2,000-5,000 | 167-417 | 56-139 | Unlimited Plan ($99/mo) |
5,000-10,000 | 417-834 | 139-278 | Agency Pack ($249/mo) |
10,000-18,000 | 834-1,500 | 278-500 | Agency Pack ($249/mo) |
18,000+ | 1,500+ | 500+ | Multiple Agency Packs |
Understanding domain setup limits
Each plan has daily domain setup limits to ensure proper infrastructure configuration:
Unlimited Plan: 5 domain setups per day
Agency Pack: 15 domain setups per day
Planning tip: If you need 21 domains for your setup, it will take approximately 5 days on the Unlimited Plan (5 domains/day) or 2 days on the Agency Pack (15 domains/day) to complete your initial infrastructure setup.
Additional costs to consider
Beyond your monthly subscription, you'll need to account for domain costs:
Domain options
Create new domains: $16.44/year for .com domains or $9.44/year for .info domains
Migrate existing domains: $5 per domain (one-time fee)
Domain renewals: $16.44 for .com domains
Domain purchase limits: You can purchase up to 5 new domains every 24 hours through the Create tab. For domain migrations, you can migrate 5 domains in the first 24 hours, then up to 20 domains every 24 hours afterward.
Total cost example
For sending 2,500 campaign emails/day with 70 new .com domains:
Monthly subscription: $99 (Unlimited Plan)
Domain cost (first year): 70 domains × $16.44 = $1,150.80
Total first-year cost: ($99 × 12) + $1,150.80 = $2,338.80
Monthly average (year 1): $194.90/month
Best practices for scaling
Start conservative
Begin with 3 inboxes per domain and gradually add more up to 5 as you scale. This gives you room to grow while maintaining deliverability.
Distribute across IPs
For the Agency Pack with 3 IPs, distribute your domains evenly across all three IPs. For example, with 84 domains, allocate 28 domains per IP.
Best practice: Keep 300-400 inboxes per dedicated IP for optimal deliverability and sender reputation management.
Account for warmup
Remember that your warmup emails count toward your daily sending limit. The 40 emails per inbox includes both warmup and campaign emails, with a typical split of 70% warmup (28 emails) and 30% campaign (12 emails). This means your actual campaign capacity is based on the 30% allocation, not the full 40 emails.
Plan for growth
If you anticipate scaling your outreach, consider starting with the Agency Pack to avoid the need to upgrade and reconfigure your infrastructure later.
When to upgrade
You should upgrade from Unlimited to Agency Pack when:
You're approaching 150+ inboxes on a single IP
You want to set up more than 5 domains per day
You need better IP isolation for different campaigns or clients
Easy upgrades: You can upgrade or downgrade your plan at any time through your subscription page. Inframail calculates prorated charges automatically.
Verify your setup
After setting up your infrastructure, verify your capacity:
Count your total active domains
Count total inboxes per domain (should be 3-5)
Calculate: Domains × Inboxes per domain × 12 campaign emails = Daily campaign capacity
Ensure your daily campaign sending stays within this capacity
What's next
Ready to get started? Sign up for Inframail
Learn how to set up your domains and inboxes efficiently
Understand email warmup best practices
Explore integration with cold email platforms like Instantly, Smartlead, or ReachInbox
Getting help
If you're unsure which plan is right for your needs or need help with capacity planning:
Contact support at [email protected]
Include your target daily/monthly campaign email volume
Mention any specific infrastructure requirements or constraints