Send a single email - Sendmux

Send a single email

curl --request POST \
  --url https://smtp.sendmux.ai/api/v1/emails/send \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "from": {
    "email": "user@example.com",
    "name": "John Smith"
  },
  "to": {
    "email": "user@example.com",
    "name": "John Smith"
  },
  "subject": "Welcome to SendMux",
  "html_body": "<string>"
}
'

{
  "ok": true,
  "data": {
    "message_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
    "status": "queued",
    "idempotent": true
  },
  "meta": {
    "request_id": "req_clxxxxxxxxxxxxxxxxxxxxxxxxx"
  }
}

POST

/

emails

/

send

Send a single email

curl --request POST \
  --url https://smtp.sendmux.ai/api/v1/emails/send \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "from": {
    "email": "user@example.com",
    "name": "John Smith"
  },
  "to": {
    "email": "user@example.com",
    "name": "John Smith"
  },
  "subject": "Welcome to SendMux",
  "html_body": "<string>"
}
'

{
  "ok": true,
  "data": {
    "message_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
    "status": "queued",
    "idempotent": true
  },
  "meta": {
    "request_id": "req_clxxxxxxxxxxxxxxxxxxxxxxxxx"
  }
}

Authorizations

Authorization

string

header

required

SendMux API key (smx_...)

Body

application/json

from

object

required

Sender address

Hide child attributes

from.email

string<email>

required

Email address

Maximum string length: 254

Example:

"user@example.com"

from.name

string

Display name

Maximum string length: 100

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

Example:

"John Smith"

to

object

required

Primary recipient

Hide child attributes

to.email

string<email>

required

Email address

Maximum string length: 254

Example:

"user@example.com"

to.name

string

Display name

Maximum string length: 100

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

Example:

"John Smith"

subject

string

required

Email subject line (max 998 chars, RFC 5322)

Required string length: 1 - 998

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

Example:

"Welcome to SendMux"

html_body

string

required

HTML email content (max 10MB)

Required string length: 1 - 10485760

text_body

string

Plain text alternative (max 10MB)

Maximum string length: 10485760

reply_to

object

Reply-To address

Hide child attributes

reply_to.email

string<email>

required

Email address

Maximum string length: 254

Example:

"user@example.com"

reply_to.name

string

Display name

Maximum string length: 100

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

Example:

"John Smith"

return_path

string<email>

Envelope sender for VERP support

Maximum string length: 254

cc

object[]

CC recipients (max 100)

Maximum array length: 100

Hide child attributes

cc.email

string<email>

required

Recipient email address

Maximum string length: 254

cc.name

string

Recipient display name

Maximum string length: 100

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

bcc

object[]

BCC recipients (max 100)

Maximum array length: 100

Hide child attributes

bcc.email

string<email>

required

Recipient email address

Maximum string length: 254

bcc.name

string

Recipient display name

Maximum string length: 100

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

custom_headers

object

Custom X-* headers to include in the email

Hide child attributes

custom_headers.{key}

string

Maximum string length: 500

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

attachments

object[]

File attachments (max 10)

Maximum array length: 10

Hide child attributes

attachments.filename

string

required

Filename with allowed extension

Required string length: 1 - 255

Example:

"invoice.pdf"

attachments.content

string

required

Base64-encoded file content

Minimum string length: 1

attachments.type

string

MIME type override

Example:

"application/pdf"

attachments.encoding

enum<string>

default:base64

Available options:

base64

idempotency_key

string

Prevents duplicate message processing (24h TTL)

Required string length: 1 - 255

Pattern: ^[a-zA-Z0-9_-]+$

Response

Email queued successfully

ok

enum<boolean>

required

Available options:

true

data

object

required

Hide child attributes

data.message_id

string<uuid>

required

Unique message identifier

data.status

enum<string>

required

Message queuing status

Available options:

queued

data.idempotent

boolean

True if this was an idempotent replay

meta

object

required

Hide child attributes

meta.request_id

string

required

Unique request identifier

Example:

"req_clxxxxxxxxxxxxxxxxxxxxxxxxx"

Errors Send a batch of emails

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