Send a batch of emails

curl --request POST \
  --url https://smtp.sendmux.ai/api/v1/emails/send/batch \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "messages": [
    {
      "from": {
        "email": "user@example.com",
        "name": "John Smith"
      },
      "to": {
        "email": "user@example.com",
        "name": "John Smith"
      },
      "subject": "Welcome to Sendmux",
      "html_body": "<string>",
      "text_body": "<string>",
      "return_path": "jsmith@example.com",
      "cc": [
        {
          "email": "jsmith@example.com",
          "name": "<string>"
        }
      ],
      "bcc": [
        {
          "email": "jsmith@example.com",
          "name": "<string>"
        }
      ],
      "custom_headers": {},
      "attachments": [
        {
          "filename": "invoice.pdf",
          "content": "<string>",
          "type": "application/pdf",
          "encoding": "base64"
        }
      ]
    }
  ]
}
'

import requests

url = "https://smtp.sendmux.ai/api/v1/emails/send/batch"

payload = { "messages": [
        {
            "from": {
                "email": "user@example.com",
                "name": "John Smith"
            },
            "to": {
                "email": "user@example.com",
                "name": "John Smith"
            },
            "subject": "Welcome to Sendmux",
            "html_body": "<string>",
            "text_body": "<string>",
            "return_path": "jsmith@example.com",
            "cc": [
                {
                    "email": "jsmith@example.com",
                    "name": "<string>"
                }
            ],
            "bcc": [
                {
                    "email": "jsmith@example.com",
                    "name": "<string>"
                }
            ],
            "custom_headers": {},
            "attachments": [
                {
                    "filename": "invoice.pdf",
                    "content": "<string>",
                    "type": "application/pdf",
                    "encoding": "base64"
                }
            ]
        }
    ] }
headers = {
    "Authorization": "Bearer <token>",
    "Content-Type": "application/json"
}

response = requests.post(url, json=payload, headers=headers)

print(response.text)

const options = {
  method: 'POST',
  headers: {Authorization: 'Bearer <token>', 'Content-Type': 'application/json'},
  body: JSON.stringify({
    messages: [
      {
        from: {email: 'user@example.com', name: 'John Smith'},
        to: {email: 'user@example.com', name: 'John Smith'},
        subject: 'Welcome to Sendmux',
        html_body: '<string>',
        text_body: '<string>',
        return_path: 'jsmith@example.com',
        cc: [{email: 'jsmith@example.com', name: '<string>'}],
        bcc: [{email: 'jsmith@example.com', name: '<string>'}],
        custom_headers: {},
        attachments: [
          {
            filename: 'invoice.pdf',
            content: '<string>',
            type: 'application/pdf',
            encoding: 'base64'
          }
        ]
      }
    ]
  })
};

fetch('https://smtp.sendmux.ai/api/v1/emails/send/batch', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

package main

import (
	"fmt"
	"strings"
	"net/http"
	"io"
)

func main() {

	url := "https://smtp.sendmux.ai/api/v1/emails/send/batch"

	payload := strings.NewReader("{\n  \"messages\": [\n    {\n      \"from\": {\n        \"email\": \"user@example.com\",\n        \"name\": \"John Smith\"\n      },\n      \"to\": {\n        \"email\": \"user@example.com\",\n        \"name\": \"John Smith\"\n      },\n      \"subject\": \"Welcome to Sendmux\",\n      \"html_body\": \"<string>\",\n      \"text_body\": \"<string>\",\n      \"return_path\": \"jsmith@example.com\",\n      \"cc\": [\n        {\n          \"email\": \"jsmith@example.com\",\n          \"name\": \"<string>\"\n        }\n      ],\n      \"bcc\": [\n        {\n          \"email\": \"jsmith@example.com\",\n          \"name\": \"<string>\"\n        }\n      ],\n      \"custom_headers\": {},\n      \"attachments\": [\n        {\n          \"filename\": \"invoice.pdf\",\n          \"content\": \"<string>\",\n          \"type\": \"application/pdf\",\n          \"encoding\": \"base64\"\n        }\n      ]\n    }\n  ]\n}")

	req, _ := http.NewRequest("POST", url, payload)

	req.Header.Add("Authorization", "Bearer <token>")
	req.Header.Add("Content-Type", "application/json")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(string(body))

}

{
  "ok": true,
  "meta": {
    "request_id": "req_clxxxxxxxxxxxxxxxxxxxxxxxxx"
  },
  "data": {
    "results": [
      {
        "index": 123,
        "message_id": "<string>",
        "error": {
          "code": "validation_error",
          "message": "<string>",
          "retryable": true,
          "param": "<string>",
          "doc_url": "<string>",
          "errors": [
            {
              "field": "to.email",
              "code": "invalid_string",
              "message": "<string>"
            }
          ]
        }
      }
    ],
    "summary": {
      "total": 123,
      "queued": 123,
      "failed": 123
    }
  }
}

{
  "ok": false,
  "error": {
    "code": "validation_error",
    "message": "<string>",
    "retryable": true,
    "param": "<string>",
    "doc_url": "<string>",
    "errors": [
      {
        "field": "to.email",
        "code": "invalid_string",
        "message": "<string>"
      }
    ]
  },
  "meta": {
    "request_id": "req_clxxxxxxxxxxxxxxxxxxxxxxxxx"
  }
}

{
  "ok": false,
  "error": {
    "code": "validation_error",
    "message": "<string>",
    "retryable": true,
    "param": "<string>",
    "doc_url": "<string>",
    "errors": [
      {
        "field": "to.email",
        "code": "invalid_string",
        "message": "<string>"
      }
    ]
  },
  "meta": {
    "request_id": "req_clxxxxxxxxxxxxxxxxxxxxxxxxx"
  }
}

{
  "ok": false,
  "error": {
    "code": "validation_error",
    "message": "<string>",
    "retryable": true,
    "param": "<string>",
    "doc_url": "<string>",
    "errors": [
      {
        "field": "to.email",
        "code": "invalid_string",
        "message": "<string>"
      }
    ]
  },
  "meta": {
    "request_id": "req_clxxxxxxxxxxxxxxxxxxxxxxxxx"
  }
}

{
  "ok": false,
  "error": {
    "code": "validation_error",
    "message": "<string>",
    "retryable": true,
    "param": "<string>",
    "doc_url": "<string>",
    "errors": [
      {
        "field": "to.email",
        "code": "invalid_string",
        "message": "<string>"
      }
    ]
  },
  "meta": {
    "request_id": "req_clxxxxxxxxxxxxxxxxxxxxxxxxx"
  }
}

{
  "ok": false,
  "error": {
    "code": "validation_error",
    "message": "<string>",
    "retryable": true,
    "param": "<string>",
    "doc_url": "<string>",
    "errors": [
      {
        "field": "to.email",
        "code": "invalid_string",
        "message": "<string>"
      }
    ]
  },
  "meta": {
    "request_id": "req_clxxxxxxxxxxxxxxxxxxxxxxxxx"
  }
}

{
  "ok": false,
  "error": {
    "code": "validation_error",
    "message": "<string>",
    "retryable": true,
    "param": "<string>",
    "doc_url": "<string>",
    "errors": [
      {
        "field": "to.email",
        "code": "invalid_string",
        "message": "<string>"
      }
    ]
  },
  "meta": {
    "request_id": "req_clxxxxxxxxxxxxxxxxxxxxxxxxx"
  }
}

{
  "ok": false,
  "error": {
    "code": "validation_error",
    "message": "<string>",
    "retryable": true,
    "param": "<string>",
    "doc_url": "<string>",
    "errors": [
      {
        "field": "to.email",
        "code": "invalid_string",
        "message": "<string>"
      }
    ]
  },
  "meta": {
    "request_id": "req_clxxxxxxxxxxxxxxxxxxxxxxxxx"
  }
}

{
  "ok": false,
  "error": {
    "code": "validation_error",
    "message": "<string>",
    "retryable": true,
    "param": "<string>",
    "doc_url": "<string>",
    "errors": [
      {
        "field": "to.email",
        "code": "invalid_string",
        "message": "<string>"
      }
    ]
  },
  "meta": {
    "request_id": "req_clxxxxxxxxxxxxxxxxxxxxxxxxx"
  }
}

{
  "ok": false,
  "error": {
    "code": "validation_error",
    "message": "<string>",
    "retryable": true,
    "param": "<string>",
    "doc_url": "<string>",
    "errors": [
      {
        "field": "to.email",
        "code": "invalid_string",
        "message": "<string>"
      }
    ]
  },
  "meta": {
    "request_id": "req_clxxxxxxxxxxxxxxxxxxxxxxxxx"
  }
}

POST

emails

send

batch

Send a batch of emails

curl --request POST \
  --url https://smtp.sendmux.ai/api/v1/emails/send/batch \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "messages": [
    {
      "from": {
        "email": "user@example.com",
        "name": "John Smith"
      },
      "to": {
        "email": "user@example.com",
        "name": "John Smith"
      },
      "subject": "Welcome to Sendmux",
      "html_body": "<string>",
      "text_body": "<string>",
      "return_path": "jsmith@example.com",
      "cc": [
        {
          "email": "jsmith@example.com",
          "name": "<string>"
        }
      ],
      "bcc": [
        {
          "email": "jsmith@example.com",
          "name": "<string>"
        }
      ],
      "custom_headers": {},
      "attachments": [
        {
          "filename": "invoice.pdf",
          "content": "<string>",
          "type": "application/pdf",
          "encoding": "base64"
        }
      ]
    }
  ]
}
'

import requests

url = "https://smtp.sendmux.ai/api/v1/emails/send/batch"

payload = { "messages": [
        {
            "from": {
                "email": "user@example.com",
                "name": "John Smith"
            },
            "to": {
                "email": "user@example.com",
                "name": "John Smith"
            },
            "subject": "Welcome to Sendmux",
            "html_body": "<string>",
            "text_body": "<string>",
            "return_path": "jsmith@example.com",
            "cc": [
                {
                    "email": "jsmith@example.com",
                    "name": "<string>"
                }
            ],
            "bcc": [
                {
                    "email": "jsmith@example.com",
                    "name": "<string>"
                }
            ],
            "custom_headers": {},
            "attachments": [
                {
                    "filename": "invoice.pdf",
                    "content": "<string>",
                    "type": "application/pdf",
                    "encoding": "base64"
                }
            ]
        }
    ] }
headers = {
    "Authorization": "Bearer <token>",
    "Content-Type": "application/json"
}

response = requests.post(url, json=payload, headers=headers)

print(response.text)

const options = {
  method: 'POST',
  headers: {Authorization: 'Bearer <token>', 'Content-Type': 'application/json'},
  body: JSON.stringify({
    messages: [
      {
        from: {email: 'user@example.com', name: 'John Smith'},
        to: {email: 'user@example.com', name: 'John Smith'},
        subject: 'Welcome to Sendmux',
        html_body: '<string>',
        text_body: '<string>',
        return_path: 'jsmith@example.com',
        cc: [{email: 'jsmith@example.com', name: '<string>'}],
        bcc: [{email: 'jsmith@example.com', name: '<string>'}],
        custom_headers: {},
        attachments: [
          {
            filename: 'invoice.pdf',
            content: '<string>',
            type: 'application/pdf',
            encoding: 'base64'
          }
        ]
      }
    ]
  })
};

fetch('https://smtp.sendmux.ai/api/v1/emails/send/batch', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

package main

import (
	"fmt"
	"strings"
	"net/http"
	"io"
)

func main() {

	url := "https://smtp.sendmux.ai/api/v1/emails/send/batch"

	payload := strings.NewReader("{\n  \"messages\": [\n    {\n      \"from\": {\n        \"email\": \"user@example.com\",\n        \"name\": \"John Smith\"\n      },\n      \"to\": {\n        \"email\": \"user@example.com\",\n        \"name\": \"John Smith\"\n      },\n      \"subject\": \"Welcome to Sendmux\",\n      \"html_body\": \"<string>\",\n      \"text_body\": \"<string>\",\n      \"return_path\": \"jsmith@example.com\",\n      \"cc\": [\n        {\n          \"email\": \"jsmith@example.com\",\n          \"name\": \"<string>\"\n        }\n      ],\n      \"bcc\": [\n        {\n          \"email\": \"jsmith@example.com\",\n          \"name\": \"<string>\"\n        }\n      ],\n      \"custom_headers\": {},\n      \"attachments\": [\n        {\n          \"filename\": \"invoice.pdf\",\n          \"content\": \"<string>\",\n          \"type\": \"application/pdf\",\n          \"encoding\": \"base64\"\n        }\n      ]\n    }\n  ]\n}")

	req, _ := http.NewRequest("POST", url, payload)

	req.Header.Add("Authorization", "Bearer <token>")
	req.Header.Add("Content-Type", "application/json")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(string(body))

}

{
  "ok": true,
  "meta": {
    "request_id": "req_clxxxxxxxxxxxxxxxxxxxxxxxxx"
  },
  "data": {
    "results": [
      {
        "index": 123,
        "message_id": "<string>",
        "error": {
          "code": "validation_error",
          "message": "<string>",
          "retryable": true,
          "param": "<string>",
          "doc_url": "<string>",
          "errors": [
            {
              "field": "to.email",
              "code": "invalid_string",
              "message": "<string>"
            }
          ]
        }
      }
    ],
    "summary": {
      "total": 123,
      "queued": 123,
      "failed": 123
    }
  }
}

{
  "ok": false,
  "error": {
    "code": "validation_error",
    "message": "<string>",
    "retryable": true,
    "param": "<string>",
    "doc_url": "<string>",
    "errors": [
      {
        "field": "to.email",
        "code": "invalid_string",
        "message": "<string>"
      }
    ]
  },
  "meta": {
    "request_id": "req_clxxxxxxxxxxxxxxxxxxxxxxxxx"
  }
}

{
  "ok": false,
  "error": {
    "code": "validation_error",
    "message": "<string>",
    "retryable": true,
    "param": "<string>",
    "doc_url": "<string>",
    "errors": [
      {
        "field": "to.email",
        "code": "invalid_string",
        "message": "<string>"
      }
    ]
  },
  "meta": {
    "request_id": "req_clxxxxxxxxxxxxxxxxxxxxxxxxx"
  }
}

{
  "ok": false,
  "error": {
    "code": "validation_error",
    "message": "<string>",
    "retryable": true,
    "param": "<string>",
    "doc_url": "<string>",
    "errors": [
      {
        "field": "to.email",
        "code": "invalid_string",
        "message": "<string>"
      }
    ]
  },
  "meta": {
    "request_id": "req_clxxxxxxxxxxxxxxxxxxxxxxxxx"
  }
}

{
  "ok": false,
  "error": {
    "code": "validation_error",
    "message": "<string>",
    "retryable": true,
    "param": "<string>",
    "doc_url": "<string>",
    "errors": [
      {
        "field": "to.email",
        "code": "invalid_string",
        "message": "<string>"
      }
    ]
  },
  "meta": {
    "request_id": "req_clxxxxxxxxxxxxxxxxxxxxxxxxx"
  }
}

{
  "ok": false,
  "error": {
    "code": "validation_error",
    "message": "<string>",
    "retryable": true,
    "param": "<string>",
    "doc_url": "<string>",
    "errors": [
      {
        "field": "to.email",
        "code": "invalid_string",
        "message": "<string>"
      }
    ]
  },
  "meta": {
    "request_id": "req_clxxxxxxxxxxxxxxxxxxxxxxxxx"
  }
}

{
  "ok": false,
  "error": {
    "code": "validation_error",
    "message": "<string>",
    "retryable": true,
    "param": "<string>",
    "doc_url": "<string>",
    "errors": [
      {
        "field": "to.email",
        "code": "invalid_string",
        "message": "<string>"
      }
    ]
  },
  "meta": {
    "request_id": "req_clxxxxxxxxxxxxxxxxxxxxxxxxx"
  }
}

{
  "ok": false,
  "error": {
    "code": "validation_error",
    "message": "<string>",
    "retryable": true,
    "param": "<string>",
    "doc_url": "<string>",
    "errors": [
      {
        "field": "to.email",
        "code": "invalid_string",
        "message": "<string>"
      }
    ]
  },
  "meta": {
    "request_id": "req_clxxxxxxxxxxxxxxxxxxxxxxxxx"
  }
}

{
  "ok": false,
  "error": {
    "code": "validation_error",
    "message": "<string>",
    "retryable": true,
    "param": "<string>",
    "doc_url": "<string>",
    "errors": [
      {
        "field": "to.email",
        "code": "invalid_string",
        "message": "<string>"
      }
    ]
  },
  "meta": {
    "request_id": "req_clxxxxxxxxxxxxxxxxxxxxxxxxx"
  }
}

{
  "ok": false,
  "error": {
    "code": "validation_error",
    "message": "<string>",
    "retryable": true,
    "param": "<string>",
    "doc_url": "<string>",
    "errors": [
      {
        "field": "to.email",
        "code": "invalid_string",
        "message": "<string>"
      }
    ]
  },
  "meta": {
    "request_id": "req_clxxxxxxxxxxxxxxxxxxxxxxxxx"
  }
}

Authorizations

Authorization

string

header

required

Sendmux API key (smx_...)

Headers

Idempotency-Key

string

Optional client-generated key to make the request idempotent for 24 hours. Replays under the same key return the cached response; a reused key with a different body returns 409 idempotency_conflict.

Maximum string length: 255

Body

application/json

messages

object[]

required

Array of email messages to send (max 100)

Required array length: 1 - 100 elements

Hide child attributes

messages.from

object

required

Sender address

Hide child attributes

messages.from.email

string<email>

required

Email address

Maximum string length: 254

Example:

"user@example.com"

messages.from.name

string

Display name

Maximum string length: 100

Pattern: ^[^\r\n]*$

Example:

"John Smith"

messages.to

object

required

Primary recipient

Hide child attributes

messages.to.email

string<email>

required

Email address

Maximum string length: 254

Example:

"user@example.com"

messages.to.name

string

Display name

Maximum string length: 100

Pattern: ^[^\r\n]*$

Example:

"John Smith"

messages.subject

string

required

Email subject line (max 998 chars, RFC 5322)

Required string length: 1 - 998

Pattern: ^[^\r\n]*$

Example:

"Welcome to Sendmux"

messages.html_body

string

required

HTML email content (max 25MB)

Required string length: 1 - 26214400

messages.text_body

string

Plain text alternative (max 25MB)

Maximum string length: 26214400

messages.reply_to

object

Reply-To address

Hide child attributes

messages.reply_to.email

string<email>

required

Email address

Maximum string length: 254

Example:

"user@example.com"

messages.reply_to.name

string

Display name

Maximum string length: 100

Pattern: ^[^\r\n]*$

Example:

"John Smith"

messages.return_path

string<email>

Envelope sender for VERP support

Maximum string length: 254

messages.cc

object[]

CC recipients (max 100)

Maximum array length: 100

Hide child attributes

messages.cc.email

string<email>

required

Recipient email address

Maximum string length: 254

messages.cc.name

string

Recipient display name

Maximum string length: 100

Pattern: ^[^\r\n]*$

messages.bcc

object[]

BCC recipients (max 100)

Maximum array length: 100

Hide child attributes

messages.bcc.email

string<email>

required

Recipient email address

Maximum string length: 254

messages.bcc.name

string

Recipient display name

Maximum string length: 100

Pattern: ^[^\r\n]*$

messages.custom_headers

object

Custom X-* headers to include in the email

Hide child attributes

messages.custom_headers.{key}

string

Maximum string length: 500

Pattern: ^[^\r\n]*$

messages.attachments

object[]

File attachments (max 10). Use attachment_id refs for uploaded files.

Maximum array length: 10

Option 1
Option 2

Hide child attributes

messages.attachments.filename

string

required

Filename with allowed extension

Required string length: 1 - 255

Example:

"invoice.pdf"

messages.attachments.content

string

required

Base64-encoded file content

Minimum string length: 1

messages.attachments.type

string

MIME type override

Example:

"application/pdf"

messages.attachments.encoding

enum<string>

default:base64

Available options:

base64

Response

Batch processed (check individual results for per-message status)

enum<boolean>

required

Available options:

true

Overview

Emails

Attachments

Send a batch of emails

Authorizations

Headers

Body

Response