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Sender accounts are email addresses used to send your ColdSend campaigns. ColdSend supports two main infrastructure types: ColdSend Native (managed) and SMTP/BYOC (bring your own credentials).
Unlike the old single-endpoint model, sender accounts are now created via type-specific endpoints: POST /sender-accounts/coldsend-native for managed accounts and POST /sender-accounts/smtp for SMTP accounts.

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Account Types

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ColdSend Native

Managed email infrastructure provided by ColdSend for optimal deliverability and simplified setup.
FeatureDescription
Automatic SetupNo SMTP/IMAP configuration needed
Deliverability OptimizationColdSend manages domain reputation
Bounce HandlingAutomatic bounce processing via Azure Communication Services
Reply TrackingNative integration via Mailcow
Endpoint: POST /api/public/v1/sender-accounts/coldsend-native 
import requests

response = requests.post(
    "https://api.coldsend.pro/api/public/v1/sender-accounts/coldsend-native",
    headers={"X-API-Key": api_key},
    json={
        "domain_id": "550e8400-e29b-41d4-a716-446655440000",
        "email_prefix": "john",
        "display_name": "John Smith from Company"
    }
)
ColdSend Native inboxes are created on domains already managed by your ColdSend workspace. You specify a domain_id and an email prefix (e.g., john → john@yourdomain.com).
Bulk creation is also supported via POST /api/public/v1/sender-accounts/coldsend-native/bulk: 
response = requests.post(
    "https://api.coldsend.pro/api/public/v1/sender-accounts/coldsend-native/bulk",
    headers={"X-API-Key": api_key},
    json={
        "domain_id": "550e8400-e29b-41d4-a716-446655440000",
        "inboxes": [
            {"email_prefix": "john", "display_name": "John Smith"},
            {"email_prefix": "sales", "display_name": "Sales Team"}
        ]
    }
)

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SMTP / BYOC (Bring Your Own Credentials)

Use your existing email accounts with custom SMTP/IMAP settings. Supported provider types: GOOGLE_WORKSPACE, OUTLOOK_365, and CUSTOM_SMTP. Endpoint: POST /api/public/v1/sender-accounts/smtp 
response = requests.post(
    "https://api.coldsend.pro/api/public/v1/sender-accounts/smtp",
    headers={"X-API-Key": api_key},
    json={
        "email_address": "outreach@company.com",
        "display_name": "John Smith from Company",
        "inbox_type": "GOOGLE_WORKSPACE",
        "daily_limit": 50,
        "smtp_host": "smtp.gmail.com",
        "smtp_port": 587,
        "smtp_username": "outreach@company.com",
        "smtp_password": "your-app-password",
        "smtp_use_tls": True,
        "imap_host": "imap.gmail.com",
        "imap_port": 993,
        "imap_username": "outreach@company.com",
        "imap_password": "your-app-password",
        "imap_use_ssl": True
    }
)
Use app-specific passwords, not your main account password. For Gmail, generate one at Google Account → Security → App Passwords.
Provider max daily limits:
ProviderMax Daily Limit
GOOGLE_WORKSPACE2,000
OUTLOOK_3655,000
CUSTOM_SMTP100,000
Bulk SMTP creation is supported via POST /api/public/v1/sender-accounts/smtp/bulk. Each inbox’s SMTP/IMAP connections are tested asynchronously. The response includes a job_id you can poll at GET /api/public/v1/sender-accounts/smtp/bulk/{job_id}/progress.

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API Endpoints

MethodEndpointDescription
GET/sender-accountsList all sender accounts (paginated, filterable)
GET/sender-accounts/{inbox_id}Get detailed sender account info
DELETE/sender-accounts/{inbox_id}Remove a sender account
POST/sender-accounts/coldsend-nativeCreate a ColdSend Native inbox
POST/sender-accounts/coldsend-native/bulkBulk create ColdSend Native inboxes (max 100)
POST/sender-accounts/smtpCreate an SMTP inbox (BYOC)
POST/sender-accounts/smtp/bulkBulk create SMTP inboxes (max 100, async)
GET/sender-accounts/smtp/bulk/{job_id}/progressTrack bulk SMTP job progress
POST/sender-accounts/bulk/deleteBulk delete sender accounts (async)
GET/sender-accounts/bulk/delete/{job_id}/progressTrack bulk delete job progress
POST/sender-accounts/{inbox_id}/test-emailSend a test email

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List & Filter Sender Accounts

GET /api/public/v1/sender-accounts supports filtering and pagination: 
response = requests.get(
    "https://api.coldsend.pro/api/public/v1/sender-accounts?inbox_type=GOOGLE_WORKSPACE&status=ACTIVE&page=1&limit=20",
    headers={"X-API-Key": api_key}
)

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Query Parameters

ParameterDescription
pagePage number (1-based, default: 1)
limitItems per page (1-100, default: 20)
inbox_typeFilter by type: COLDSEND, GOOGLE_WORKSPACE, OUTLOOK_365, CUSTOM_SMTP
statusFilter by status: ACTIVE, PAUSED, DISABLED
searchSearch by email address
sort_bySort field: email_address, inbox_type, created_at, health_score
sort_orderSort direction: asc, desc

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Response Format

{
  "success": true,
  "message": "Retrieved 3 sender accounts",
  "sender_accounts": [
    {
      "inbox_id": "750e8400-e29b-41d4-a716-446655440000",
      "email_address": "john@company.com",
      "display_name": "John Smith",
      "inbox_type": "GOOGLE_WORKSPACE",
      "overall_status": "ACTIVE",
      "daily_limit": 50,
      "emails_sent_today": 12,
      "health_score": 95.0,
      "created_at": "2024-01-15T10:30:00Z"
    }
  ],
  "pagination": {
    "page": 1,
    "limit": 20,
    "total": 3,
    "pages": 1,
    "has_next": false,
    "has_prev": false
  }
}

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Account Status

StatusDescription
ACTIVEReady to use in campaigns
PAUSEDTemporarily disabled, can be reactivated
DISABLEDCannot be used — may require re-authentication

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Inbox Types

The API uses these inbox_type values consistently:
ValueDescription
COLDSENDColdSend Native managed inbox
GOOGLE_WORKSPACEGoogle Workspace via SMTP/IMAP
OUTLOOK_365Microsoft 365 via SMTP/IMAP
CUSTOM_SMTPAny custom SMTP provider

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Next Steps

Provider Configuration

Detailed SMTP setup guides for Google Workspace, Microsoft 365, and custom providers.

Campaigns Overview

Learn how to assign sender accounts to campaigns.