Transactional and inbound email — send, threads, drafts, attachments, hosted templates, domains and DNS verification, deliverability, suppressions, account and billing. 32 paths, 47 operations, bearer token or session cookie.
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openapi: 3.1.0
info:
title: SendHQ 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.
- name: Drafts and attachments
description: Build composer flows with private attachment storage.
- name: Hosted templates
description: Draft, render, test, version, publish, and send reusable content.
- name: Domains
description: Provision sender identities and understand DNS verification state.
- name: Inbound email
description: Create addresses and work with received conversations.
- name: Deliverability
description: Inspect events, reputation outcomes, and blocked recipients.
- name: Account and billing
description: Session-authenticated workspace administration.
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'
/drafts:
post:
operationId: post_drafts
tags:
- Drafts and attachments
summary: Create a composer draft
description: Create a composer draft
security:
- bearerAuth: []
parameters: []
responses:
'201':
description: Successful response
content:
application/json:
schema:
type: object
properties:
id:
type: string
attachments:
type: array
items: {}
required:
- id
- attachments
additionalProperties: false
example:
id: dr_…
attachments: []
'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
format: email
to:
type: array
items:
type: string
format: email
subject:
type: string
required:
- from
- to
- subject
additionalProperties: false
example:
from: hello@example.com
to:
- customer@example.net
subject: Hello
get:
operationId: get_drafts
tags:
- Drafts and attachments
summary: List composer drafts
description: List composer drafts
security:
- bearerAuth: []
parameters: []
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'
/drafts/{id}:
get:
operationId: get_drafts_id
tags:
- Drafts and attachments
summary: Retrieve a draft and attachments
description: Retrieve a draft and 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
attachments:
type: array
items: {}
required:
- id
- attachments
additionalProperties: false
example:
id: dr_…
attachments: []
'400':
$ref: '#/components/responses/BadRequest'
'401':
$ref: '#/components/responses/Unauthorized'
'404':
$ref: '#/components/responses/NotFound'
'429':
$ref: '#/components/responses/RateLimited'
put:
operationId: put_drafts_id
tags:
- Drafts and attachments
summary: Replace draft content
description: Replace draft content
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
required:
- id
additionalProperties: false
example:
id: dr_…
'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
format: email
to:
type: array
items:
type: string
format: email
subject:
type: string
text:
type: string
required:
- from
- to
- subject
- text
additionalProperties: false
example:
from: hello@example.com
to:
- customer@example.net
subject: Updated subject
text: Updated body
delete:
operationId: delete_drafts_id
tags:
- Drafts and attachments
summary: Discard a draft
description: Discard a draft
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'
/drafts/{id}/attachments:
post:
operationId: post_drafts_id_attachments
tags:
- Drafts and attachments
summary: Upload an attachment to a draft
description: Upload raw file bytes. Set Content-Type and X-Filename. A message can contain at most
10 files and 10 MB total.
security:
- bearerAuth: []
parameters:
- name: id
in: path
required: true
schema:
type: string
- name: X-Filename
in: header
required: false
schema:
type: string
responses:
'201':
description: Successful response
content:
application/json:
schema:
type: object
properties:
id:
type: string
filename:
type: string
sizeBytes:
type: integer
available:
type: boolean
required:
- id
- filename
- sizeBytes
- available
additionalProperties: false
example:
id: att_…
filename: invoice.pdf
sizeBytes: 48231
available: true
'400':
$ref: '#/components/responses/BadRequest'
'401':
$ref: '#/components/responses/Unauthorized'
'404':
$ref: '#/components/responses/NotFound'
'429':
$ref: '#/components/responses/RateLimited'
/attachments/{id}:
get:
operationId: get_attachments_id
tags:
- Drafts and attachments
summary: Download a private attachment
description: Download a private attachment
security:
- bearerAuth: []
parameters:
- name: id
in: path
required: true
schema:
type: string
responses:
'200':
description: Successful response
content:
application/octet-stream:
schema:
type: string
contentEncoding: binary
'400':
$ref: '#/components/responses/BadRequest'
'401':
$ref: '#/components/responses/Unauthorized'
'404':
$ref: '#/components/responses/NotFound'
'429':
$ref: '#/components/responses/RateLimited'
delete:
operationId: delete_attachments_id
tags:
- Drafts and attachments
summary: Delete a private attachment
description: Delete a private attachment
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'
/sending-identities:
get:
operationId: get_sending_identities
tags:
- Drafts and attachments
summary: List verified sender identities
description: List verified sender identities
security:
- bearerAuth: []
parameters: []
responses:
'200':
description: Successful response
content:
application/json:
schema:
type: object
properties:
domains:
type: array
items: {}
addresses:
type: array
items: {}
localParts:
type: array
items: {}
required:
- domains
- addresses
- localParts
additionalProperties: false
example:
domains: []
addresses: []
localParts: []
'400':
$ref: '#/components/responses/BadRequest'
'401':
$ref: '#/components/responses/Unauthorized'
'404':
$ref: '#/components/responses/NotFound'
'429':
$ref: '#/components/responses/RateLimited'
/templates:
get:
operationId: get_templates
tags:
- Hosted templates
summary: List hosted templates
description: List hosted templates
security:
- bearerAuth: []
parameters:
- name: lifecycle
in: query
required: false
schema:
type: string
enum:
- active
- archived
- all
- name: query
in: query
required: false
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'
post:
operationId: post_templates
tags:
- Hosted templates
summary: Create a hosted template
description: Create a hosted template
security:
- bearerAuth: []
parameters: []
responses:
'201':
description: Successful response
content:
application/json:
schema:
type: object
properties:
template:
type: object
properties:
id:
type: string
key:
type: string
required:
- id
- key
additionalProperties: false
required:
- template
additionalProperties: false
example:
template:
id: tmpl_…
key: account-welcome
'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:
name:
type: string
key:
type: string
starter:
type: string
required:
- name
- key
- starter
additionalProperties: false
example:
name: Account welcome
key: account-welcome
starter: welcome
/templates/{id}:
get:
operationId: get_templates_id
tags:
- Hosted templates
summary: Retrieve drafts, releases, and usage
description: Retrieve drafts, releases, and usage
security:
- bearerAuth: []
parameters:
- name: id
in: path
required: true
schema:
type: string
responses:
'200':
description: Successful response
content:
application/json:
schema:
type: object
properties:
template:
type: object
properties:
id:
type: string
required:
- id
additionalProperties: false
versions:
type: array
items: {}
draft: {}
activeVersion: {}
usage:
type: array
items: {}
required:
- template
- versions
- draft
- activeVersion
- usage
additionalProperties: false
example:
template:
id: tmpl_…
versions: []
draft: null
activeVersion: null
usage:
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# Full source: https://raw.githubusercontent.com/api-evangelist/sendhq/refs/heads/main/openapi/sendhq-api-openapi.yml