Sending Email with SendNeo

Sending email with SendNeo

SendNeo's email API is compatible with the common Resend request shape. All endpoints use https://sendneo.yorkermedia.com/api and a bearer key.

Authorization: Bearer sn_live_...
Content-Type: application/json

`POST /emails`

Field	Type	Required	Notes
`from`	string	yes	A verified sender, optionally with a display name.
`to`	string or array	yes	One or more recipients.
`subject`	string	yes	Subject line.
`html`	string	no	HTML body. Supply `text` too for a plain-text alternative.
`text`	string	no	Plain-text body.
`cc`	string or array	no	Carbon-copy recipients.
`bcc`	string or array	no	Blind-copy recipients.
`reply_to`	string or array	no	Reply address or addresses.
`headers`	object	no	Additional message headers.
`tags`	array	no	Application labels for filtering and reporting.
`scheduled_at`	ISO 8601 string	no	Deliver at a future time.
`attachments`	array	no	Base64 file content plus a filename.

A minimal request looks like this:

curl https://sendneo.yorkermedia.com/api/emails \
  -X POST \
  -H "Authorization: Bearer $SENDNEO_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "from": "Acme <hello@mail.example.com>",
    "to": "person@example.net",
    "subject": "Receipt",
    "html": "<p>Thanks for your order.</p>",
    "text": "Thanks for your order."
  }'

The response is an object containing the message ID:

{"id":"email_01J..."}

Use GET /emails/{id} to read the current status.

Batch sends

POST /emails/batch accepts up to 100 email objects in one request. Each object uses the same fields as POST /emails. Keep each recipient's message separate when personalization or privacy matters.

curl https://sendneo.yorkermedia.com/api/emails/batch \
  -X POST \
  -H "Authorization: Bearer $SENDNEO_API_KEY" \
  -H "Content-Type: application/json" \
  -d '[
    {"from":"Acme <hello@mail.example.com>","to":"a@example.net","subject":"Hi A","text":"Hello A"},
    {"from":"Acme <hello@mail.example.com>","to":"b@example.net","subject":"Hi B","text":"Hello B"}
  ]'

Scheduling and canceling

Add scheduled_at to an email request with an ISO 8601 timestamp. Store the returned ID. Before delivery, cancel it with:

curl https://sendneo.yorkermedia.com/api/emails/email_01J.../cancel \
  -X POST \
  -H "Authorization: Bearer $SENDNEO_API_KEY"

A message that has already been delivered cannot be canceled. Check GET /emails/{id} if a cancellation races with delivery.

Idempotency

Send the Idempotency-Key header when a timeout or network retry could submit the same message twice. Keys are retained for 24 hours. Reusing a key with the same request lets your retry receive the original result; changing the request under an existing key is an error.

Idempotency-Key: order-8472-confirmation

Use an application-level unique value such as an order ID plus message purpose. Do not use one constant key for all mail.

Attachments

Each attachment contains base64 content and a filename. The combined attachment size for one message is limited to 7 MB.

{
  "attachments": [
    {
      "filename": "receipt.pdf",
      "content": "JVBERi0xLjQK..."
    }
  ]
}

Base64 increases the wire size, so check the decoded files before building the request. Use a short, safe filename and do not place credentials in an attachment.

Errors and HTTP codes

Errors use one consistent shape:

{"error":{"type":"invalid_request","message":"The from address is not verified"}}

Code	Meaning
`400`	Malformed JSON or an invalid combination of fields.
`401`	Missing, malformed, or invalid bearer key.
`403`	The key is valid but the action is not allowed, such as live delivery during review.
`404`	The message, domain, or other resource does not exist.
`409`	A conflicting operation, including an idempotency conflict.
`413`	Request or attachment size is too large.
`422`	The fields parse but fail validation, such as an unverified sender.
`429`	The key exceeded 10 requests per second. Honor `Retry-After` before retrying.
`500`	A temporary server error. Retry safely with the same idempotency key.

A retry loop should retry 429 and suitable 5xx responses, respect Retry-After, and preserve the original idempotency key. Do not blindly retry a 4xx validation error.

For newsletters, use the audiences and broadcasts API described in Newsletters. For delivery events, configure webhooks.