Creating Your First Mailbox

Step 1: Create Your Mailboxes

There are a few ways to set up mailboxes—pick the one that works best for your needs.

Option 1: Bulk Upload via CSV

Best for creating 10 or more mailboxes:

• Download the CSV template
• Fill in first name, last name, email, and password
• Upload the completed file
• Verify that mailboxes were created successfully

Note: This process usually takes about 10 minutes.

Option 2: Auto-Generate

Quick and easy for up to 5 mailboxes:

• Click Add Mailbox
• Select your domain
• Choose the number of mailboxes to create (max: 5)
• Click Generate, then Purchase

Option 3: Manual Setup

Prefer more control? You can create each mailbox individually.

• Click Add Mailbox
• Select your domain
• Enter a username, password (min. 8 characters), and name
• Click Add to Cart, then Purchase

Step 2: Export Mailboxes to Your Sending Platform

Once your mailboxes are ready:

1. Go to the Export Mailbox section
2. Choose your sending platform (e.g., SmartLead, Instantly, Reply.io)
3. Click to download the CSV

Your file will include:

• Email addresses
• Passwords
• Pre-filled warm-up settings
  
  

Step 3: Warm-Up Strategy

To protect your sender reputation, we recommend the following warm-up timeline:

A few key notes:

• Warm-up begins immediately after domain setup
• Ideal setup consists of 3 mailboxes per domain or 1 mailbox per subdomain
• Target 2–3 month inbox lifespan
• Mailboxes may burn around 45–60 days depending on usage and copy fatigue
• Default premium warm up in Mission Inbox is 50% Gmail / 50% Outlook
• Customize warmup based on provider (Gmail, Outlook, others)
• Mission Inbox v3 uses adaptive warm-up AI — adjusts sending speed based on:
  • • Reply rate
    • Bounce rate
    • Mailbox age

• Recommended: Rotate inboxes every 45–60 days to maintain high performance across campaigns

How Mission Inbox Supports Your Deliverability

• Mission Inbox now hosts its own email infrastructure (not dependent on Mailgun/SendGrid)
• IPs are monitored & auto-replaced every 7 minutes if blacklisted
• Integrated with Glockapps for inbox placement testing
• Backend upgraded with load balancers to handle high send volume
• Mission Inbox v3 introduces a dedicated delivery engine optimized specifically for cold email—built entirely in-house.
• Zero third-party SMTPs like SendGrid or Mailgun are used unless manually configured by the client.
• The new engine uses dynamic IP warming, automated throttling, and adaptive domain routing to improve inbox placement.

Tips to Keep in Mind

• You can create mailboxes before domain verification (manually), but you won’t be able to send until DNS verification is complete

• Subdomains help spread out your sending—use options like get., try., go., or join. (Avoid mail. or email.)

• Check DNS records carefully if you're doing setup manually

• Use tags to keep mailboxes organized by campaign or provider in your sequencer

Need Help?

Don’t worry—we’ve got your back. Your dedicated onboarding specialist is always available to walk you through domain setup or troubleshoot any issues.

All Set?

Once your mailboxes are verified and exported, you’re ready to start sending. Let’s get your campaigns in motion!