Send, retrieve, search, reply, and inspect delivery events.
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openapi: 3.2.0
info:
title: SendHQ Emails and threads API
version: '2026-08-23'
description: Send and receive expected email, manage verified domains and hosted templates, and inspect delivery outcomes.
servers:
- url: https://sendhq.cc/api/v1
tags:
- name: Emails and threads
description: Send, retrieve, search, reply, and inspect delivery events.
paths:
/emails:
post:
operationId: post_emails
tags:
- Emails and threads
summary: Send one email
description: Send transactional HTML, text, or hosted-template content from a verified workspace domain.
security:
- bearerAuth: []
parameters:
- name: Idempotency-Key
in: header
required: false
schema:
type: string
responses:
'201':
description: Successful response
content:
application/json:
schema:
type: object
properties:
id:
type: string
providerMessageId:
type: string
threadId:
type: string
required:
- id
- providerMessageId
- threadId
additionalProperties: false
example:
id: em_…
providerMessageId: provider-id
threadId: em_…
'400':
$ref: '#/components/responses/BadRequest'
'401':
$ref: '#/components/responses/Unauthorized'
'404':
$ref: '#/components/responses/NotFound'
'429':
$ref: '#/components/responses/RateLimited'
requestBody:
required: true
content:
application/json:
schema:
type: object
properties:
from:
type: string
to:
type: array
items:
type: string
format: email
subject:
type: string
html:
type: string
text:
type: string
required:
- from
- to
- subject
- html
- text
additionalProperties: false
example:
from: Acme <hello@example.com>
to:
- customer@example.net
subject: Welcome aboard
html: <h1>Welcome</h1><p>Your workspace is ready.</p>
text: Welcome. Your workspace is ready.
get:
operationId: get_emails
tags:
- Emails and threads
summary: List sent and received email
description: List sent and received email
security:
- bearerAuth: []
parameters:
- name: direction
in: query
required: false
schema:
type: string
enum:
- in
- out
- name: status
in: query
required: false
schema:
type: string
- name: domain
in: query
required: false
schema:
type: string
- name: inbox_id
in: query
required: false
schema:
type: string
- name: from
in: query
required: false
schema:
type: string
- name: to
in: query
required: false
schema:
type: string
- name: unread
in: query
required: false
schema:
type: boolean
- name: after
in: query
required: false
schema:
type: string
format: date-time
- name: before
in: query
required: false
schema:
type: string
format: date-time
- name: query
in: query
required: false
schema:
type: string
- name: limit
in: query
required: false
schema:
type: integer
minimum: 1
- name: offset
in: query
required: false
schema:
type: integer
minimum: 0
responses:
'200':
description: Successful response
content:
application/json:
schema:
type: object
properties:
data:
type: array
items: {}
count:
type: integer
required:
- data
- count
additionalProperties: false
example:
data: []
count: 0
'400':
$ref: '#/components/responses/BadRequest'
'401':
$ref: '#/components/responses/Unauthorized'
'404':
$ref: '#/components/responses/NotFound'
'429':
$ref: '#/components/responses/RateLimited'
/emails/batch:
post:
operationId: post_emails_batch
tags:
- Emails and threads
summary: Send up to 100 individualized messages
description: Send up to 100 individualized messages
security:
- bearerAuth: []
parameters:
- name: Idempotency-Key
in: header
required: false
schema:
type: string
responses:
'201':
description: Successful response
content:
application/json:
schema:
type: object
properties:
data:
type: array
items:
type: object
properties:
index:
type: integer
ok:
type: boolean
id:
type: string
required:
- index
- ok
- id
additionalProperties: false
count:
type: integer
successful:
type: integer
failed:
type: integer
required:
- data
- count
- successful
- failed
additionalProperties: false
example:
data:
- index: 0
ok: true
id: em_…
count: 1
successful: 1
failed: 0
'207':
description: Successful response with partial outcomes
content:
application/json:
schema:
type: object
properties:
data:
type: array
items:
type: object
properties:
index:
type: integer
ok:
type: boolean
id:
type: string
required:
- index
- ok
- id
additionalProperties: false
count:
type: integer
successful:
type: integer
failed:
type: integer
required:
- data
- count
- successful
- failed
additionalProperties: false
example:
data:
- index: 0
ok: true
id: em_…
count: 1
successful: 1
failed: 0
'400':
$ref: '#/components/responses/BadRequest'
'401':
$ref: '#/components/responses/Unauthorized'
'404':
$ref: '#/components/responses/NotFound'
'429':
$ref: '#/components/responses/RateLimited'
requestBody:
required: true
content:
application/json:
schema:
type: object
properties:
emails:
type: array
items:
type: object
properties:
from:
type: string
to:
type: array
items:
type: string
format: email
subject:
type: string
html:
type: string
text:
type: string
required:
- from
- to
- subject
- html
- text
additionalProperties: false
required:
- emails
additionalProperties: false
example:
emails:
- from: Acme <hello@example.com>
to:
- customer@example.net
subject: Welcome aboard
html: <h1>Welcome</h1><p>Your workspace is ready.</p>
text: Welcome. Your workspace is ready.
/emails/{id}:
get:
operationId: get_emails_id
tags:
- Emails and threads
summary: Retrieve an email and its attachments
description: Retrieve an email and its attachments
security:
- bearerAuth: []
parameters:
- name: id
in: path
required: true
schema:
type: string
responses:
'200':
description: Successful response
content:
application/json:
schema:
type: object
properties:
id:
type: string
direction:
type: string
status:
type: string
attachments:
type: array
items: {}
required:
- id
- direction
- status
- attachments
additionalProperties: false
example:
id: em_…
direction: out
status: sent
attachments: []
'400':
$ref: '#/components/responses/BadRequest'
'401':
$ref: '#/components/responses/Unauthorized'
'404':
$ref: '#/components/responses/NotFound'
'429':
$ref: '#/components/responses/RateLimited'
patch:
operationId: patch_emails_id
tags:
- Emails and threads
summary: Mark an email read or unread
description: Mark an email read or unread
security:
- bearerAuth: []
parameters:
- name: id
in: path
required: true
schema:
type: string
responses:
'200':
description: Successful response
content:
application/json:
schema:
type: object
properties:
id:
type: string
readAt:
type: string
format: date-time
required:
- id
- readAt
additionalProperties: false
example:
id: em_…
readAt: '2026-08-23T12:00:00.000Z'
'400':
$ref: '#/components/responses/BadRequest'
'401':
$ref: '#/components/responses/Unauthorized'
'404':
$ref: '#/components/responses/NotFound'
'429':
$ref: '#/components/responses/RateLimited'
requestBody:
required: true
content:
application/json:
schema:
type: object
properties:
read:
type: boolean
required:
- read
additionalProperties: false
example:
read: true
delete:
operationId: delete_emails_id
tags:
- Emails and threads
summary: Delete a retained email
description: Delete a retained email
security:
- bearerAuth: []
parameters:
- name: id
in: path
required: true
schema:
type: string
responses:
'200':
description: Successful response
content:
application/json:
schema:
type: object
properties:
ok:
type: boolean
required:
- ok
additionalProperties: false
example:
ok: true
'400':
$ref: '#/components/responses/BadRequest'
'401':
$ref: '#/components/responses/Unauthorized'
'404':
$ref: '#/components/responses/NotFound'
'429':
$ref: '#/components/responses/RateLimited'
/emails/{id}/events:
get:
operationId: get_emails_id_events
tags:
- Emails and threads
summary: List delivery events for an email
description: List delivery events for an email
security:
- bearerAuth: []
parameters:
- name: id
in: path
required: true
schema:
type: string
responses:
'200':
description: Successful response
content:
application/json:
schema:
type: object
properties:
data:
type: array
items: {}
count:
type: integer
required:
- data
- count
additionalProperties: false
example:
data: []
count: 0
'400':
$ref: '#/components/responses/BadRequest'
'401':
$ref: '#/components/responses/Unauthorized'
'404':
$ref: '#/components/responses/NotFound'
'429':
$ref: '#/components/responses/RateLimited'
/threads/{id}:
get:
operationId: get_threads_id
tags:
- Emails and threads
summary: Retrieve a conversation chronologically
description: Retrieve a conversation chronologically
security:
- bearerAuth: []
parameters:
- name: id
in: path
required: true
schema:
type: string
responses:
'200':
description: Successful response
content:
application/json:
schema:
type: object
properties:
id:
type: string
data:
type: array
items: {}
count:
type: integer
required:
- id
- data
- count
additionalProperties: false
example:
id: em_…
data: []
count: 0
'400':
$ref: '#/components/responses/BadRequest'
'401':
$ref: '#/components/responses/Unauthorized'
'404':
$ref: '#/components/responses/NotFound'
'429':
$ref: '#/components/responses/RateLimited'
components:
schemas:
Error:
type: object
required:
- error
properties:
error:
type: object
required:
- message
- status
properties:
message:
type: string
status:
type: integer
code:
type:
- string
- 'null'
responses:
Unauthorized:
description: Missing or invalid authentication
content:
application/json:
schema:
$ref: '#/components/schemas/Error'
RateLimited:
description: A usage or reputation limit was reached
content:
application/json:
schema:
$ref: '#/components/schemas/Error'
BadRequest:
description: Invalid request
content:
application/json:
schema:
$ref: '#/components/schemas/Error'
NotFound:
description: Resource not found
content:
application/json:
schema:
$ref: '#/components/schemas/Error'
securitySchemes:
bearerAuth:
type: http
scheme: bearer
bearerFormat: re_…
description: Workspace API key. Keep it server-side.
sessionCookie:
type: apiKey
in: cookie
name: sendhq_session_v2
description: Browser session used for account administration.