Auth

POST

smtp

auth

cURL

curl --request POST \
  --url https://bytesend.cloud/api/v1/smtp/auth \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "username": "<string>",
  "password": "<string>"
}
'

import requests

url = "https://bytesend.cloud/api/v1/smtp/auth"

payload = {
    "username": "<string>",
    "password": "<string>"
}
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({username: '<string>', password: '<string>'})
};

fetch('https://bytesend.cloud/api/v1/smtp/auth', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://bytesend.cloud/api/v1/smtp/auth",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => json_encode([
    'username' => '<string>',
    'password' => '<string>'
  ]),
  CURLOPT_HTTPHEADER => [
    "Authorization: Bearer <token>",
    "Content-Type: application/json"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

package main

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

func main() {

	url := "https://bytesend.cloud/api/v1/smtp/auth"

	payload := strings.NewReader("{\n  \"username\": \"<string>\",\n  \"password\": \"<string>\"\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))

}

HttpResponse<String> response = Unirest.post("https://bytesend.cloud/api/v1/smtp/auth")
  .header("Authorization", "Bearer <token>")
  .header("Content-Type", "application/json")
  .body("{\n  \"username\": \"<string>\",\n  \"password\": \"<string>\"\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://bytesend.cloud/api/v1/smtp/auth")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Post.new(url)
request["Authorization"] = 'Bearer <token>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"username\": \"<string>\",\n  \"password\": \"<string>\"\n}"

response = http.request(request)
puts response.read_body

{
  "valid": true
}

{
  "valid": false,
  "message": "<string>"
}

Authenticate SMTP credentials. This endpoint is called by the SMTP relay server to validate client credentials during authentication.

Usage

The SMTP relay server calls this endpoint during the AUTH phase to verify that the provided username and API key are valid. The username can be a custom team-specific SMTP username or the global default (bytesend).

Authentication

This endpoint does not require Bearer token authentication. Instead, it accepts the credentials directly in the request body.

Request Body

username (string, required): The SMTP username. Can be:
- A custom team SMTP username (configured in team settings)
- The global default: bytesend
- Or any username if using an API key for a team with remote auth enabled
password (string, required): The API key to verify. This is used as the password in SMTP AUTH PLAIN or AUTH LOGIN flows.

Response

200 Success:

{
  "valid": true
}

401 Unauthorized:

{
  "valid": false,
  "message": "Invalid API key or username"
}

Examples

curl -X POST https://bytesend.cloud/api/v1/smtp/auth \
  -H "Content-Type: application/json" \
  -d '{
    "username": "bytesend",
    "password": "YOUR_API_KEY"
  }'

const response = await fetch('https://bytesend.cloud/api/v1/smtp/auth', {
  method: 'POST',
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify({
    username: 'bytesend',
    password: 'YOUR_API_KEY'
  })
});

const data = await response.json();
console.log(data); // { valid: true } or { valid: false, message: "..." }

import requests

response = requests.post(
  'https://bytesend.cloud/api/v1/smtp/auth',
  json={
    'username': 'bytesend',
    'password': 'YOUR_API_KEY'
  }
)

print(response.json())  # { 'valid': True } or { 'valid': False, 'message': '...' }

Notes

This endpoint is fire-and-forget from the perspective of the SMTP relay. Failures are logged but do not block the SMTP handshake.
The endpoint does not perform rate limiting separate from the standard API rate limits.
For custom team SMTP usernames, ensure the API key belongs to that team.

Authorizations

Authorization

string

header

required

Bearer authentication header of the form Bearer <token>, where <token> is your auth token.

Body

application/json

username

string

required

SMTP username (typically the custom team username or default 'bytesend')

password

string

required

API key used as password for SMTP authentication

Response

Credentials are valid

valid

enum<boolean>

required

Available options:

true

cURL

curl --request POST \
  --url https://bytesend.cloud/api/v1/smtp/auth \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "username": "<string>",
  "password": "<string>"
}
'

import requests

url = "https://bytesend.cloud/api/v1/smtp/auth"

payload = {
    "username": "<string>",
    "password": "<string>"
}
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({username: '<string>', password: '<string>'})
};

fetch('https://bytesend.cloud/api/v1/smtp/auth', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://bytesend.cloud/api/v1/smtp/auth",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => json_encode([
    'username' => '<string>',
    'password' => '<string>'
  ]),
  CURLOPT_HTTPHEADER => [
    "Authorization: Bearer <token>",
    "Content-Type: application/json"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

package main

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

func main() {

	url := "https://bytesend.cloud/api/v1/smtp/auth"

	payload := strings.NewReader("{\n  \"username\": \"<string>\",\n  \"password\": \"<string>\"\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))

}

HttpResponse<String> response = Unirest.post("https://bytesend.cloud/api/v1/smtp/auth")
  .header("Authorization", "Bearer <token>")
  .header("Content-Type", "application/json")
  .body("{\n  \"username\": \"<string>\",\n  \"password\": \"<string>\"\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://bytesend.cloud/api/v1/smtp/auth")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Post.new(url)
request["Authorization"] = 'Bearer <token>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"username\": \"<string>\",\n  \"password\": \"<string>\"\n}"

response = http.request(request)
puts response.read_body

{
  "valid": true
}

{
  "valid": false,
  "message": "<string>"
}

API Reference

Emails

Contact Books

Contacts

Domains

Campaigns

Analytics

SMTP

Usage

Authentication

Request Body

Response

Examples

Notes

Authorizations

Body

Response

​Usage

​Authentication

​Request Body

​Response

​Examples

​Notes

Authorizations

Body

Response

Usage

Authentication

Request Body

Response

Examples

Notes