Send email

POST /emails/send — payload, response, and templates.

Main transactional send endpoint.

POST https://api.mailingcore.com/emails/send
Authorization: Bearer mc_live_xxxx
X-Tenant-Id: clxxxxxxxx
Content-Type: application/json

Required scope: email:send.

Request body

{
  "to": "[email protected]",
  "subject": "Welcome to MailingCore",
  "htmlBody": "<h1>Hello</h1><p>Thanks for signing up.</p>",
  "textBody": "Hello. Thanks for signing up.",
  "fromEmail": "[email protected]",
  "fromName": "Your App",
  "replyTo": "[email protected]",
  "tags": ["welcome"],
  "metadata": { "userId": "123" },
  "idempotencyKey": "welcome-123-v1",
  "templateVersionId": "clxversion...",
  "projectId": "clxproject...",
  "unsubscribeLang": "en"
}

Fields

Field	Required	Description
`to`	Yes	Recipient email
`subject`	Yes	Subject line (max 998 characters)
`htmlBody`	Yes*	Message HTML (*or use `templateVersionId`)
`textBody`	No	Plain-text fallback
`fromEmail`	No	Sender; domain must be verified
`fromName`	No	Display name for sender
`replyTo`	No	Reply-to address
`tags`	No	Tags for filtering logs
`metadata`	No	Free-form JSON for your integration
`idempotencyKey`	No	Safe retries (same key = same response)
`templateVersionId`	No	Published template version
`projectId`	No	SMTP project (advanced)
`unsubscribeLang`	No	Language for campaign unsubscribe page

Response (async)

{
  "id": "clxlog...",
  "status": "QUEUED",
  "queued": true,
  "position": 2
}

In development you can force synchronous delivery with ?sync=true.

Quota headers

Each response may include:

X-Quota-Limit: 5000
X-Quota-Used: 420
X-Quota-Percentage: 8
X-Quota-Warning: true

Details in Monthly quota.

Batch send

POST /emails/batch — up to 100 recipients per request. Same scope email:send.