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How to Set Up Cold Email Domains and Inboxes

Learn how to purchase domains, add inboxes, and manage the warmup process for CallSine’s cold email infrastructure.

Updated over a month ago

Available on all CallSine plans, including Free Trial.

View all products and plans.

Overview

CallSine manages its own cold email infrastructure so you can scale outreach safely and maintain deliverability. Every inbox follows reputation best practices to ensure consistent inbox placement.


You can now purchase new domains and create inboxes directly in the platform.
All new inboxes complete a four-week Warmup period before they are ready to send at scale.

Step 1: Purchase a Domain

  1. Click the Email icon in the left menu bar.

  2. In the pop-up, select Domains.

  3. On the Domains page, click Buy Domain in the top-right corner.

  4. Enter your company domain (for example, callsine.com). CallSine will suggest available variations.

  5. Click Get Price to view the cost.

  6. Click Buy to move forward with purchase.

  7. Enter your billing information and confirm by clicking Purchase.

Approval Process

  • Domains are reviewed within 24 hours.

  • Once approved, validation (DNS setup) completes automatically within about one hour.

  • You’ll receive a notification when the domain is approved and validated.

Step 2: Add Mail Accounts

After approval, you can create mailboxes for the new domain.

  1. In the Cold Email Infrastructure table, locate your domain.

  2. Click Add Mailbox on the right side of the row.

  3. Enter:

    • First Name and Last Name

    • Email Address (for example, jane@newdomain.com)

    • Password (used to manage the mailbox)

  4. Click Create Mailbox.

Notes

  • Each domain supports up to three inboxes.

  • All new inboxes enter a four-week Warmup period to build sending reputation.

Step 3: Mailbox Warmup and Readiness

During Warmup, the Ready for Use column in the table will show as Pending.
Once Warmup completes, the status changes to Ready, and you’ll receive a notification.
At that point, the inbox is live and available for use in your Agents.

Setup Flow Summary

  1. Buy Domain — Billed to the card on file

  2. Approval — Reviewed within 24 hours

  3. Validation — DNS configuration completes automatically (≈1 hour)

  4. Add Mail Accounts — Up to 3 per domain

  5. Warmup — 4 weeks to build reputation

  6. Ready for Use — Inbox becomes active in CallSine

Related Articles
How CallSine's Cold Email Infrastructure Works
How the Outreach Agent Manages Email and LinkedIn Safely
How to Add and Manage Sender Accounts
How to Read and Use the Cold Email Infrastructure Table
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