How to calculate your email sending capacity and choose the right plan

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 inbox

Step 2: Calculate domains needed

Total Domains = Total Inboxes ÷ 3 inboxes per domain

Round 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 - $129/month

Send up to 80,000 cold emails per month (per workday). Great for small agencies.

What's included:

Free setup in seconds
1 Dedicated US IP ready-to-go
FREE automation to setup emails
Unlimited Email Inboxes
1-on-1 Deliverability Consultant
Priority Support
No extra cost per inbox
Unlimited Domain Setups Per Day
API Access

Agency Pack - $327/month

Send up to 300,000 cold emails per month (per workday). Most popular plan.

What's included:

Free setup in seconds
3 Dedicated US IPs ready-to-go
FREE automation to setup emails
Unlimited Email Inboxes
1-on-1 Deliverability Consultant
Priority Support
No extra cost per inbox
Unlimited Domain Setups Per Day
API Access

Annual plans (30% discount)

Both plans are available with annual billing at a 30% discount:

Annual Unlimited: $90.30/month (billed annually)
Annual Agency Pack: $228.90/month (billed annually)

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 ($129/mo)
2,000-5,000	167-417	56-139	Unlimited Plan ($129/mo)
5,000-10,000	417-834	139-278	Agency Pack ($327/mo)
10,000-18,000	834-1,500	278-500	Agency Pack ($327/mo)
18,000+	1,500+	500+	Multiple Agency Packs

Domain setup

Both Inframail plans include unlimited domain setups per day, so you can configure all your domains in one session without daily limits. You can purchase domains directly from the Inframail platform or bring domains you already own for $5 per domain (one-time fee).

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 on the Unlimited Plan:

Monthly subscription: $129 (Unlimited Plan)
Domain purchases: 70 domains × $16.44 = $1,150.80
Total first-year cost: ($129 × 12) + $1,150.80 = $2,698.80
Monthly average (year 1): ~$225/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 need higher sending capacity (300,000 cold emails/mo vs. 80,000 for Unlimited)
You need additional dedicated IPs for better IP isolation across 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

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