The Mailcamp transactional API lets your application send one-to-one system emails through Mailcamp. Use it for messages such as password resets, login alerts, account notifications, receipts, and invoices.
Transactional sending is separate from bulk marketing campaigns and may have its own plan limits and rate limits.
Mailcamp shows transactional API documentation inside your account.
Open Mailcamp.
Go to Support.
Open API docs.
Review the endpoint examples and authentication instructions.
Use the transactional endpoint to enqueue a single message.
Endpoint: POST /api/v1/smtp.
Authentication: Authorization: Bearer YOUR_API_KEY.
Include sender, recipient, subject, and message content in the request.
Check the response for the message ID and request ID.
If the request is accepted, Mailcamp queues the email for delivery and updates delivery status through transactional logs and provider events.
Use a verified sender domain for the best result.
If from_email is empty, Mailcamp may use an available default sender.
If the sender domain is not verified, Mailcamp may use the active sending domain if one is available.
If no active sending domain is available, Mailcamp may fall back to @mailcamp.io.
Authenticate your sending domain before using the API in production.
Transactional API usage is controlled by your plan.
Rate limits are enforced per plan.
Requests that exceed the limit may return 429.
Monitor your transactional sending credits and usage.
Use retries carefully so your application does not create duplicate messages.
Use transactional logs to review messages sent through the API.
Open the transactional log page in Mailcamp.
Review recipient, sender, subject, and message details.
Open a message detail when you need to inspect content or attachments.
Use webhook history for delivery event troubleshooting.