1. Core Concepts
  • Welcome to the Cold Mail Reseller API
  • Get Started
    • Overview
    • Authentication
    • Quick Start
  • Core Concepts
    • Users
    • Domains
    • DNS Management
    • Mailboxes
    • Subscriptions
    • Pre-Warmup
    • Domain Renewal
    • 1+ Year Subscriptions
    • Mailbox Warmup
    • Platform Exports
    • OAuth Exports
    • Sandbox API
  • API Reference
    • Users
      • List Users
      • Get User
      • Create User
      • Update User
      • Delete User
    • Geo
      • List Countries
      • List States
    • Domains
      • Domain Renewal
        • Get Domain Renewal Prices
        • Renew Domains
        • Toggle Domain Auto-Renew
      • Get Domains by User
      • Check Domain Availability
      • Check Single Domain Availability
      • Check Workspace Existence
      • Set Domain Forwarding
      • Set Email Forwarding
      • Delete Domains
    • DNS
      • Get DNS Records
      • Add DNS Records
      • Update DNS Record
      • Update Nameservers
      • Delete DNS Record
    • Mailboxes
      • List Mailboxes
      • Get Mailboxes by User
      • Get Mailbox
      • Get Admin Mailbox Details
      • Update Mailbox Details
      • Delete Mailbox
    • Mailbox Warmup
      • Add Warmup to Mailbox
      • Toggle Warmup
      • Update Warmup Settings
      • Set Warmup Status
      • Disable Warmup
    • Orders
      • Get Order Status
      • Get Order Details
      • Create Order
      • Create Order (JSON)
      • Create Mailbox Order (JSON)
      • Process Order
    • Subscriptions
      • 1+ Year Subscription
        • Recreate Subscription
      • Get Subscriptions
      • Renew Subscriptions
      • Cancel Subscription
      • Toggle Auto-Renewal
    • Exports
      • Platform Exports
        • Get Platform Credentials
        • Add Platform Credential
        • Export Mailboxes to Platform
        • Remove Platform Credential
      • OAuth Exports
        • Perform OAuth
        • Add Client ID to Domains
    • Pre-Warmup
      • Sandbox
        • Get Sandbox Pre-warmup Domains
        • Order Sandbox Pre-warmup
        • Reset Sandbox Pre-warmup
      • Get Pre-warmup Domains
      • Order Pre-warmup
    • Placement Test
      • Create Placement Order
      • Get Placement Reports
  • Resources
    • Errors
    • Rate Limits
    • Pagination
    • Sandbox
    • MCP
  • Webhooks
    • Overview
    • Events
      • Domain Events
      • Mailbox Events
      • Subscription Events
      • Prewarmup Events
      • Mailbox Warmup Events
  • Schemas
    • Error
    • Success
    • MessageResponse
    • User
    • Domain
    • ErrorResponse
    • Mailbox
    • Subscription
    • DnsRecord
    • Error Response
    • Pagination Meta
    • Action Error Response
    • PrewarmupOrderResult
    • OrderCreationResult
  1. Core Concepts

Pre-Warmup

Pre-warmed mailboxes have already completed the warmup process and are ready for high-volume cold email campaigns immediately.

How Pre-Warmup Works#

CMR maintains a inventory of pre-warmed mailboxes.
Browse available inventory, place an order specifying the domains and service provider, and CMR transfers those mailboxes to your user's account.
They're immediately usable for sending.
Browse inventory   →  GET /pre-warmup
Place order        →  POST /pre-warmup/order?userId=
Receive webhook    →  prewarmup.order.success
Export to platform →  POST /exports/outreach-app

Available Endpoints#

MethodEndpointDescription
GET/pre-warmupBrowse available pre-warmed inventory
POST/pre-warmup/order?userId=Place a pre-warmup order

Key Concepts#

Browse inventory
Place an order

Webhook Events#

EventDescription
prewarmup.order.successMailboxes transferred and ready — payload includes mailboxId, email, status, and warmupDaysCompleted for each mailbox
prewarmup.order.failedOrder failed — reason field indicates the cause

Sandbox Testing#

INFO
Sandbox endpoints use the cmr-x-sandbox-api-key header — not the standard cmr-x-api-key.
EndpointDescription
GET /sandbox/pre-warmupBrowse sandbox inventory
POST /sandbox/pre-warmup/order?userId=Place a sandbox order
DELETE /sandbox/pre-warmup/reset?userId=Reset all sandbox state for the user
Control the outcome by sending a cmr-x-sandbox-scenario header on the order request:
Header valueSimulated outcome
simulate:prewarmup-order-successOrder completes successfully (default)
simulate:prewarmup-order-failedOrder fails entirely
The sandbox request body follows the same structure as production.
See the full Sandbox API reference for every sandboxed endpoint and scenario key.

Scenarios#

Standard Pre-Warmup Purchase#

1
Browse inventory
GET /pre-warmup — filter by serviceProvider and check available domains.
2
Place order
POST /pre-warmup/order?userId= — pass the order array, serviceProvider, and any OAuth details.
3
Receive webhook
Listen for prewarmup.order.success. The payload contains all provisioned mailboxes.

Test with Sandbox#

1
Browse sandbox inventory
GET /sandbox/pre-warmup — check available test domains.
2
Place sandbox order
POST /sandbox/pre-warmup/order?userId= — send simulate: prewarmup-order-success header to control the outcome.
3
Verify webhook handler
Confirm your prewarmup.order.success handler receives and processes the payload correctly.
4
Reset state
DELETE /sandbox/pre-warmup/reset?userId= — clean up between test runs.

Avoid These Common Issues#

Not listening for the webhook — A 201 response only confirms the order was queued. Mailboxes are not ready until prewarmup.order.success fires. Do not export before receiving it.
Insufficient wallet balance — Orders fail if the partner wallet cannot cover the cost. Check balance before placing large orders.
Missing provider config — Microsoft orders without microsoftOauthRoute are rejected immediately. Google OAuth export requires the full google object with googleOauthRoute, clientId, and appName.
Not resetting sandbox state — Old sandbox data can interfere with subsequent tests. Call DELETE /sandbox/pre-warmup/reset between runs.

Next Steps#

Platform Exports
Export pre-warmed mailboxes to EmailBison immediately after the order completes.
Prewarmup Events
Full webhook payloads for prewarmup.order.success and prewarmup.order.failed.
Mailbox Warmup
Standard warmup for mailboxes you provision yourself.
Modified at 2026-08-05 16:12:50
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