Errors

An error answers with a 4xx or 5xx status and this body:

{
  "error": {
    "code": "domain_not_verified",
    "message": "example.com is not a verified domain of this account"
  }
}

Test the code. The message is written for you, in English, and its wording can change.

Codes

Status	Code	Cause	What to do
400	invalid_request	A field is missing or has the wrong type.	Read message: it names the field.
400	invalid_email	An address is not valid, the subject spans several lines, or a custom header is refused.	Fix the value named in message.
401	missing_api_key	No Authorization: Bearer header, or a value that is not a MailPush key.	Send your key in the header.
401	invalid_api_key	The key does not exist or was revoked.	Create a key in the dashboard.
404	email_not_found	No such email for this account.	Check the id and the key’s account.
413	payload_too_large	The request is larger than 10 MB.	Shrink the content.
422	domain_not_verified	The domain of from is not verified by your account.	Verify the domain.
422	template_not_found	Your account has no template with the alias or id given in template.	Check the alias on the template’s page in the dashboard.
422	template_not_published	The template exists but has no published version.	Publish it in the dashboard.
422	missing_template_data	data lacks a variable the template prints.	Add the names listed in message to data.
429	rate_limited	More than 10 requests in a second with one key.	Wait for Retry-After, 1 second, and send again.
429	daily_quota_exceeded	The account reached its recipients for the day.	Wait for Retry-After, or ask for a higher limit.
500	internal_error	Something failed on our side.	Send again with the same Idempotency-Key.

Retrying

Retry rate_limited, internal_error and network failures. Send an Idempotency-Key so a retry cannot send the email twice.

Do not retry the other codes: the same request gets the same answer. daily_quota_exceeded clears at midnight UTC, and its Retry-After header gives the seconds left.

The Node.js SDK follows these rules for you.