MailBridgeAPI Sending API
Send and validate email through the selected mailbox.
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OpenAPI Specification
openapi: 3.2.0
info:
title: MailBridge Sending API
summary: Turn your own mailbox into a secure email API.
version: 2026-10-20.1
description: 'MailBridgeAPI connects a mailbox you own to authenticated HTTP endpoints.
Use the account API key together with a mailbox API key to send email, read incoming messages, search activity and monitor mailbox readiness without distributing SMTP or IMAP passwords across projects.
Compatible connections include standard SMTP/IMAP, Gmail, Microsoft 365, Yahoo Mail, Zoho Mail and iCloud Mail. Provider capabilities and limits still apply.
Keep both API keys in server-side environment variables or a secret manager. Never expose them in browser code, public repositories or mobile application bundles.'
termsOfService: https://mailbridgeapi.com/terms-of-service/
contact:
name: MailBridgeAPI Support
url: https://mailbridgeapi.com/contact/
email: info@mailbridgeapi.com
license:
name: MailBridgeAPI Terms of Service
url: https://mailbridgeapi.com/terms-of-service/
x-logo:
url: https://mailbridgeapi.com/logo-mark.svg
altText: MailBridgeAPI
servers:
- url: https://api.mailbridgeapi.com
description: Production API
security:
- AccountKey: []
MailboxKey: []
tags:
- name: Sending
description: Send and validate email through the selected mailbox.
paths:
/sendemail/:
post:
summary: Send an email through your connected mailbox
description: Sends one message through the mailbox selected by `apikeybox`. A successful SMTP acceptance is recorded in MailBridgeAPI. When sent-copy archiving is enabled, storage in the mailbox Sent folder happens asynchronously. Set `skip_sent_copy=true` to exclude this message from that queue.
security: []
requestBody:
required: true
content:
application/x-www-form-urlencoded:
schema:
$ref: '#/components/schemas/SendEmailPayload'
examples:
textEmail:
summary: Plain-text email
value:
apikey: YOUR_ACCOUNT_API_KEY
apikeybox: YOUR_MAILBOX_API_KEY
recipient_email: jane@example.com
mail_subject: Hello from MailBridgeAPI
mail_body: This message was sent through my connected mailbox.
format: text
from_source: my-application
responses:
'200':
description: Request processed. Check `result.error` and `result.sent` for the provider result.
content:
application/json:
schema:
$ref: '#/components/schemas/LegacySendResponse'
example:
result:
error: '0'
sent: OK
id: msg_example
'400':
$ref: '#/components/responses/BadRequest'
'401':
$ref: '#/components/responses/Unauthorized'
'429':
$ref: '#/components/responses/TooManyRequests'
'500':
$ref: '#/components/responses/ServerError'
tags:
- Sending
operationId: sendEmail
x-codeSamples:
- lang: cURL
label: cURL
source: 'curl -X POST ''https://api.mailbridgeapi.com/sendemail/'' \
+ -H ''Content-Type: application/x-www-form-urlencoded'' \
+ --data-urlencode ''apikey=YOUR_ACCOUNT_API_KEY'' \
+ --data-urlencode ''apikeybox=YOUR_MAILBOX_API_KEY'' \
+ --data-urlencode ''recipient_email=jane@example.com'' \
+ --data-urlencode ''mail_subject=Hello from MailBridgeAPI'' \
+ --data-urlencode ''mail_body=Sent through my connected mailbox'' \
+ --data-urlencode ''format=text'''
- lang: PHP
label: PHP
source: "<?php\n$payload = http_build_query([\n 'apikey' => getenv('MAILBRIDGE_API_KEY'),\n 'apikeybox' => getenv('MAILBRIDGE_BOX_KEY'),\n 'recipient_email' => 'jane@example.com',\n 'mail_subject' => 'Hello from MailBridgeAPI',\n 'mail_body' => 'Sent through my connected mailbox',\n 'format' => 'text',\n]);\n$context = stream_context_create(['http' => [\n 'method' => 'POST',\n 'header' => 'Content-Type: application/x-www-form-urlencoded',\n 'content' => $payload,\n]]);\n$result = file_get_contents('https://api.mailbridgeapi.com/sendemail/', false, $context);\necho $result;"
/email/validate/:
post:
summary: Validate a send request without sending email
requestBody:
required: true
content:
application/json:
schema:
$ref: '#/components/schemas/ValidateEmail'
application/x-www-form-urlencoded:
schema:
$ref: '#/components/schemas/ValidateEmail'
responses:
'200':
description: Validation errors and warnings. data.sends_email is always false.
'400':
$ref: '#/components/responses/BadRequest'
'401':
$ref: '#/components/responses/Unauthorized'
'429':
$ref: '#/components/responses/TooManyRequests'
'500':
$ref: '#/components/responses/ServerError'
tags:
- Sending
operationId: validateEmail
components:
schemas:
ValidateEmail:
type: object
required:
- recipient_email
- mail_subject
- mail_body
properties:
recipient_email:
type: string
format: email
mail_subject:
type: string
mail_body:
type: string
maxLength: 1048576
format:
type: string
enum:
- html
- text
default: html
Error:
type: object
required:
- ok
- error
- meta
properties:
ok:
const: false
error:
type: object
required:
- code
- message
properties:
code:
type: string
message:
type: string
additionalProperties: false
meta:
$ref: '#/components/schemas/Meta'
additionalProperties: false
SendEmailPayload:
type: object
additionalProperties: false
required:
- apikey
- apikeybox
- recipient_email
- mail_subject
- mail_body
properties:
apikey:
type: string
description: Account API key.
example: YOUR_ACCOUNT_API_KEY
apikeybox:
type: string
description: Mailbox API key.
example: YOUR_MAILBOX_API_KEY
recipient_email:
type: string
format: email
description: Primary recipient.
mail_subject:
type: string
minLength: 1
maxLength: 998
mail_body:
type: string
minLength: 1
description: HTML or plain-text message body.
sender_email:
type: string
format: email
description: Optional sender override. The provider must authorize this address.
sender_name:
type: string
maxLength: 200
reply_email:
type: string
format: email
reply_name:
type: string
maxLength: 200
email_cc1:
type: string
format: email
email_cc2:
type: string
format: email
email_cc3:
type: string
format: email
format:
type: string
enum:
- html
- text
default: html
charset:
type: string
default: UTF-8
attachmentBase64_1:
type: string
format: byte
description: First attachment encoded as base64.
attachmentBase64_name_1:
type: string
description: Filename for the first attachment.
attachmentBase64_2:
type: string
format: byte
description: Second attachment encoded as base64.
attachmentBase64_name_2:
type: string
description: Filename for the second attachment.
embeddedImage:
type: string
format: uri
description: Public image URL to embed inline.
embeddedImage_cid:
type: string
description: Content ID referenced from HTML as `cid:VALUE`.
unsubscribe:
oneOf:
- type: boolean
- type: integer
enum:
- 0
- 1
default: false
description: Append the configured unsubscribe footer.
from_source:
type: string
maxLength: 80
pattern: ^[A-Za-z0-9._:-]+$
default: api
description: Source label stored with sent activity, such as `wordpress` or `crm`.
allow_self_signed:
oneOf:
- type: boolean
- type: string
enum:
- 'yes'
- 'no'
default: false
description: Allow a self-signed SMTP certificate. Keep disabled unless the mailbox server requires it.
skip_sent_copy:
type: boolean
default: false
description: Never queue this message for an IMAP Sent-folder copy.
mail_message_id:
type: string
description: Optional RFC 5322 Message-ID without angle brackets.
mail_in_reply_to:
type: string
description: Optional parent Message-ID used to preserve a conversation thread.
mail_references:
type: string
description: Space-separated Message-ID values used to preserve a conversation thread.
mail_auto_submitted:
type: string
enum:
- auto-generated
- auto-replied
description: Optional Auto-Submitted header value for automated mail.
Pagination:
type: object
properties:
page:
type: integer
minimum: 1
per_page:
type: integer
minimum: 1
total:
type: integer
minimum: 0
pages:
type: integer
minimum: 0
next_page_token:
type:
- string
- 'null'
LegacySendResponse:
type: object
required:
- result
properties:
result:
type: object
required:
- error
- sent
properties:
error:
type: string
description: '`0` indicates success.'
sent:
type: string
description: '`OK` indicates that the provider accepted the send.'
id:
type: string
description: MailBridgeAPI message identifier when available.
Meta:
type: object
properties:
request_id:
type: string
api_version:
type: string
timestamp:
type: string
format: date-time
pagination:
$ref: '#/components/schemas/Pagination'
additionalProperties: false
responses:
ServerError:
description: The mailbox provider rejected the operation or an internal service error occurred.
content:
application/json:
schema:
$ref: '#/components/schemas/Error'
TooManyRequests:
description: The MailBridgeAPI or provider request limit was reached. Do not retry email sends blindly.
headers:
Retry-After:
description: Seconds to wait before retrying when supplied.
schema:
type: integer
minimum: 1
content:
application/json:
schema:
$ref: '#/components/schemas/Error'
Unauthorized:
description: The account API key or mailbox API key is missing, invalid, expired or not allowed to access this mailbox.
content:
application/json:
schema:
$ref: '#/components/schemas/Error'
BadRequest:
description: The request is missing a required value or contains an invalid parameter.
content:
application/json:
schema:
$ref: '#/components/schemas/Error'
securitySchemes:
AccountKey:
type: apiKey
in: header
name: X-API-Key
description: 'Account API key. New endpoints also accept the value as an `Authorization: Bearer` token.'
MailboxKey:
type: apiKey
in: header
name: X-Mailbox-Key
description: Mailbox API key selecting exactly one configured mailbox.
AccountKeyQuery:
type: apiKey
in: query
name: apikey
description: Account API key used by legacy-compatible endpoints. Prefer headers for new integrations when supported.
MailboxKeyQuery:
type: apiKey
in: query
name: apikeybox
description: Mailbox API key used by legacy-compatible endpoints.
externalDocs:
description: Interactive documentation, guides and live endpoint tester
url: https://mailbridgeapi.com/doc/