Add, verify and manage sender domains, tracking and return-path subdomains
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openapi: 3.2.0
info:
title: SMTP2GO SENDER DOMAINS API
version: 3.0.4
description: The SMTP2GO v3 REST API for sending transactional email and SMS, managing sender domains and single sender emails, SMTP users, API keys, IP allow lists and IP auth, templates, webhooks, suppressions, subaccounts, dedicated IPs, email archive, activity search and delivery statistics. Every operation is a POST (with a PATCH variant on two paths) carrying a JSON body; authentication is an API key supplied in the X-Smtp2go-Api-Key header or as an api_key field in the request body.
contact:
name: SMTP2GO Support
url: https://support.smtp2go.com/
termsOfService: https://www.smtp2go.com/terms/
x-harvest:
source: https://developers.smtp2go.com/mcp
method: MCP tools/call get-endpoint, one call per path+method, assembled verbatim
harvested: '2026-08-13'
server_info:
name: SMTP2GO-API-Docs
version: 3.0.4
note: SMTP2GO does not publish a single fetchable OpenAPI URL; the ReadMe registry path answers 429 to non-browser clients. The provider's own remote MCP server returns the authoritative OpenAPI 3.1.0 fragment for each endpoint anonymously, and those 73 fragments are merged here without modification.
servers:
- url: https://api.smtp2go.com/v3
description: Regionless
- url: https://us-api.smtp2go.com/v3
description: US Region
- url: https://eu-api.smtp2go.com/v3
description: EU Region
- url: https://au-api.smtp2go.com/v3
description: AU Region
security:
- sec0: []
tags:
- name: SENDER DOMAINS
description: Add, verify and manage sender domains, tracking and return-path subdomains
paths:
/domain/add:
post:
tags:
- SENDER DOMAINS
summary: Add a sender domain
description: Add a sender domain to your account. Note that you must own any domains you wish to include in this list, as you will be required to verify and authenticate the emails sent via that domain. Find full details in the Sender Domains Guide.
operationId: add-sender-domain
requestBody:
content:
application/json:
schema:
type: object
required:
- domain
properties:
domain:
type: string
description: Domain to add as a sender domain
tracking_subdomain:
type: string
description: An optional subdomain used for click or open tracking and unsubscribe links
returnpath_subdomain:
type: string
description: An optional subdomain to use as a return-path subdomain
auto_verify:
type: boolean
description: If true, verify the domain now removing the need to call the 'domain/verify' endpoint or wait for the periodic verification every 7 minutes.<br> <br> <strong>Note:</strong> In order to successfully complete the verification, the 'tracking_subdomain' and 'returnpath_subdomain' must be configured in the domain DNS and propagated.
default: true
requisition_ssl:
type: boolean
description: If true, requisition an SSL certificate for the tracking domain once verification is complete
default: true
subaccount_id:
type: string
description: If you wish to make this API call on behalf of a subaccount then include its unique ID here
subaccount_access:
type: object
description: Allow subaccounts to send from verified sender domains on the master account
properties:
subaccounts:
type: array
description: A list of subaccount_ids to be given access. ID's can be found by querying <code>/subaccounts/search</code>
future_subaccounts:
type: boolean
description: If set to true, will automatically add any new subaccounts to the access list
responses:
'200':
description: Domain added
content:
application/json:
examples:
Result:
value:
request_id: e023461c-8c86-11e9-b984-408d5cce2644
data:
domains:
- domain:
fulldomain: example.com
subdomain: null
domain: example
suffix: com
dkim_selector: s123456
dkim_verified: true
dkim_status: ''
dkim_value: dkim.smtp2go.net
rpath_selector: em123456
rpath_verified: true
rpath_status: ''
rpath_value: return.smtp2go.net
setup_link: <url>
trackers:
- fulldomain: link.example.com
subdomain: link
domain: example
suffix: com
cname_verified: false
cname_status: ''
cname_value: ''
enabled: false
schema:
type: object
required:
- request_id
- data
properties:
request_id:
type: string
example: e023461c-8c86-11e9-b984-408d5cce2644
data:
type: object
required:
- domains
properties:
domains:
type: array
items:
type: object
properties:
domain:
type: object
required:
- dkim_value
- domain
- suffix
- rpath_status
- rpath_value
- dkim_status
- subdomain
- fulldomain
- dkim_selector
- setup_link
properties:
dkim_value:
type: string
example: dkim.smtp2go.net
domain:
type: string
example: example
suffix:
type: string
example: com
rpath_selector:
type: string
example: ''
rpath_status:
type: string
example: ''
rpath_verified:
type: boolean
example: true
default: true
rpath_value:
type: string
example: return.smtp2go.net
dkim_status:
type: string
example: ''
dkim_verified:
type: boolean
example: true
default: true
subdomain: {}
fulldomain:
type: string
example: example.com
dkim_selector:
type: string
example: s123456
setup_link:
type: string
description: A URL that can be used to automate DNS additions
trackers:
type: array
items:
type: object
required:
- cname_value
- cname_status
properties:
cname_value:
type: string
example: ''
cname_status:
type: string
example: ''
cname_verified:
type: boolean
example: false
default: true
domain:
type: string
example: example
suffix:
type: string
example: com
subdomain:
type: string
example: link
enabled:
type: boolean
example: false
default: true
fulldomain:
type: string
example: link.example.com
subaccount_access:
type: object
properties:
subaccounts:
type: array
description: A list of subaccount IDs that were given access the sender domain.
future_subaccounts:
type: boolean
description: If true, any new subaccounts added will automatically be given access.
default: false
'400':
description: '400'
content:
application/json:
examples:
Result:
value:
request_id: 22e5acba-43bf-11e6-ae42-408d5cce2644
data:
error: You do not have permission to access this API endpoint
error_code: E_ApiResponseCodes.ENDPOINT_PERMISSION_DENIED
schema:
type: object
properties:
request_id:
type: string
example: 22e5acba-43bf-11e6-ae42-408d5cce2644
data:
type: object
properties:
error:
type: string
example: You do not have permission to access this API endpoint
error_code:
type: string
example: E_ApiResponseCodes.ENDPOINT_PERMISSION_DENIED
deprecated: false
/domain/remove:
post:
tags:
- SENDER DOMAINS
summary: Remove a sender domain
description: Remove a sender domain from your account
operationId: remove-sender-domain
requestBody:
content:
application/json:
schema:
type: object
required:
- domain
properties:
domain:
type: string
description: Sender Domain to delete.
subaccount_id:
type: string
description: If you wish to make this API call on behalf of a subaccount then include its unique ID here
responses:
'200':
description: Sender domain removed
content:
application/json:
examples:
Result:
value:
request_id: 117607da-8c88-11e9-96fa-408d5cce2644
data:
domains: []
schema:
type: object
required:
- request_id
- data
properties:
request_id:
type: string
example: e023461c-8c86-11e9-b984-408d5cce2644
data:
type: object
required:
- domains
properties:
domains:
type: array
items:
type: object
properties:
domain:
type: object
required:
- dkim_value
- domain
- suffix
- rpath_status
- rpath_value
- dkim_status
- subdomain
- fulldomain
- dkim_selector
properties:
dkim_value:
type: string
example: dkim.smtp2go.net
domain:
type: string
example: example
suffix:
type: string
example: com
rpath_selector:
type: string
example: ''
rpath_status:
type: string
example: ''
rpath_verified:
type: boolean
example: true
default: true
rpath_value:
type: string
example: return.smtp2go.net
dkim_status:
type: string
example: ''
dkim_verified:
type: boolean
example: true
default: true
subdomain: {}
fulldomain:
type: string
example: example.com
dkim_selector:
type: string
example: s123456
trackers:
type: array
items:
type: object
required:
- cname_value
- cname_status
properties:
cname_value:
type: string
example: ''
cname_status:
type: string
example: ''
cname_verified:
type: boolean
example: false
default: true
domain:
type: string
example: example
suffix:
type: string
example: com
subdomain:
type: string
example: link
enabled:
type: boolean
example: false
default: true
fulldomain:
type: string
example: link.example.com
subaccount_access:
type: object
properties:
subaccounts:
type: array
description: A list of subaccount IDs that were given access the sender domain.
future_subaccounts:
type: boolean
description: If true, any new subaccounts added will automatically be given access.
default: false
'400':
description: '400'
content:
application/json:
examples:
Result:
value:
request_id: 22e5acba-43bf-11e6-ae42-408d5cce2644
data:
error: You do not have permission to access this API endpoint
error_code: E_ApiResponseCodes.ENDPOINT_PERMISSION_DENIED
schema:
type: object
properties:
request_id:
type: string
example: 22e5acba-43bf-11e6-ae42-408d5cce2644
data:
type: object
properties:
error:
type: string
example: You do not have permission to access this API endpoint
error_code:
type: string
example: E_ApiResponseCodes.ENDPOINT_PERMISSION_DENIED
deprecated: false
/domain/returnpath:
post:
tags:
- SENDER DOMAINS
summary: Edit the return-path subdomain
description: A Return Path Subdomain is used to instruct the server where to return emails that are not deliverable (ie. Bounces). This endpoint allows you to edit a Return Path Subdomain for a particular sender domain. Full details can be found in the Sender Domain Guide.
operationId: edit-return-path-domain
requestBody:
content:
application/json:
schema:
type: object
required:
- domain
- old_subdomain
- new_subdomain
properties:
domain:
type: string
description: The sender domain to edit the return-path subdomain for
old_subdomain:
type: string
description: The domains old return-path subdomain
default: returns
new_subdomain:
type: string
description: The domains new return-path subdomain
default: return
subaccount_id:
type: string
description: If you wish to make this API call on behalf of a subaccount then include its unique ID here
responses:
'200':
description: Return-path subdomain edited
content:
application/json:
examples:
Result:
value:
request_id: 86758976-934b-11e7-b5be-480fcf01a6f2
data:
domains:
- domain:
fulldomain: example.com
subdomain: null
domain: example
suffix: com
dkim_selector: s123456
dkim_verified: true
dkim_status: ''
dkim_value: dkim.smtp2go.net
rpath_selector: returns
rpath_verified: true
rpath_status: ''
rpath_value: return.smtp2go.net
trackers:
- fulldomain: link.example.co.uk
subdomain: link
domain: example
suffix: co.uk
cname_verified: false
cname_status: 'Lookup CNAME(link.example.co.uk.) on ns1.falcoda.net returned no results
Lookup CNAME(link.example.co.uk.) on ns1.falcoda.net returned no results
Lookup CNAME(link.example.co.uk.) on ns2.falcoda.net returned no results
Lookup CNAME(link.example.co.uk.) on ns2.falcoda.net returned no results'
cname_value: ''
enabled: false
schema:
type: object
required:
- request_id
- data
properties:
request_id:
type: string
example: e023461c-8c86-11e9-b984-408d5cce2644
data:
type: object
required:
- domains
properties:
domains:
type: array
items:
type: object
properties:
domain:
type: object
required:
- dkim_value
- domain
- suffix
- rpath_status
- rpath_value
- dkim_status
- subdomain
- fulldomain
- dkim_selector
properties:
dkim_value:
type: string
example: dkim.smtp2go.net
domain:
type: string
example: example
suffix:
type: string
example: com
rpath_selector:
type: string
example: ''
rpath_status:
type: string
example: ''
rpath_verified:
type: boolean
example: true
default: true
rpath_value:
type: string
example: return.smtp2go.net
dkim_status:
type: string
example: ''
dkim_verified:
type: boolean
example: true
default: true
subdomain: {}
fulldomain:
type: string
example: example.com
dkim_selector:
type: string
example: s123456
trackers:
type: array
items:
type: object
required:
- cname_value
- cname_status
properties:
cname_value:
type: string
example: ''
cname_status:
type: string
example: ''
cname_verified:
type: boolean
example: false
default: true
domain:
type: string
example: example
suffix:
type: string
example: com
subdomain:
type: string
example: link
enabled:
type: boolean
example: false
default: true
fulldomain:
type: string
example: link.example.com
subaccount_access:
type: object
properties:
subaccounts:
type: array
description: A list of subaccount IDs that were given access the sender domain.
future_subaccounts:
type: boolean
description: If true, any new subaccounts added will automatically be given access.
default: false
'400':
description: '400'
content:
application/json:
examples:
Result:
value:
request_id: 22e5acba-43bf-11e6-ae42-408d5cce2644
data:
error: You do not have permission to access this API endpoint
error_code: E_ApiResponseCodes.ENDPOINT_PERMISSION_DENIED
schema:
type: object
properties:
request_id:
type: string
example: 22e5acba-43bf-11e6-ae42-408d5cce2644
data:
type: object
properties:
error:
type: string
example: You do not have permission to access this API endpoint
error_code:
type: string
example: E_ApiResponseCodes.ENDPOINT_PERMISSION_DENIED
deprecated: false
/domain/subaccount_access:
post:
tags:
- SENDER DOMAINS
summary: Edit subaccount access
description: Allow subaccounts to send from verified sender domains on the master account.
operationId: edit-subaccount-access
requestBody:
content:
application/json:
schema:
type: object
required:
- domain
- subaccounts
properties:
domain:
type: string
description: The sender domain to edit subaccount access for
subaccounts:
type: array
description: A list of subaccount_ids to be given access. ID's can be found by querying <code>/subaccounts/search</code>
future_subaccounts:
type: boolean
description: If set to true, will automatically add any new subaccounts to the access list
default: false
responses:
'200':
description: Subaccount access updated
content:
application/json:
schema:
type: object
properties:
domain:
type: string
description: The sender domain that was modified.
subaccounts:
type: array
description: A list of subaccount IDs that were given access the sender domain.
future_subaccounts:
type: boolean
description: If true, any new subaccounts added will automatically be given access.
examples:
Result:
value:
request_id: 6d4706c4-54c9-483d-b141-4f16a9c26879
data:
domain: my-verified-domain.com
subaccounts: []
future_subaccounts: false
'400':
description: '400'
content:
application/json:
examples:
Result:
value:
request_id: 22e5acba-43bf-11e6-ae42-408d5cce2644
data:
error: You do not have permission to access this API endpoint
error_code: E_ApiResponseCodes.ENDPOINT_PERMISSION_DENIED
schema:
type: object
properties:
request_id:
type: string
example: 22e5acba-43bf-11e6-ae42-408d5cce2644
data:
type: object
properties:
error:
type: string
example: You do not have permission to access this API endpoint
error_code:
type: string
example: E_ApiResponseCodes.ENDPOINT_PERMISSION_DENIED
deprecated: false
/domain/tracking:
post:
tags:
- SENDER DOMAINS
summary: Edit the tracking subdomain
description: A Tracking Subdomain is used to monitor your email opens and clicks. This endpoint allows you to edit a tracking subdomain for a particular sender domain. Full details can be found in the Sender Domain Guide.
operationId: edit-tracking-domain
requestBody:
content:
application/json:
schema:
type: object
required:
- domain
- old_subdomain
- new_subdomain
properties:
domain:
type: string
description: The sender domain to edit the tracking subdomain for
default: null
old_subdomain:
type: string
description: The domains old tracking subdomain
default: track
new_subdomain:
type: string
description: The domains new tracking subdomain
default: link
subaccount_id:
type: string
description: If you wish to make this API call on behalf of a subaccount then include its unique ID here
responses:
'200':
description: Tracking subdomain edited
content:
application/json:
examples:
Result:
value:
request_id: 86758976-934b-11e7-b5be-480fcf01a6f2
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# Full source: https://raw.githubusercontent.com/api-evangelist/smtp2go/refs/heads/main/openapi/smtp2go-sender-domains-api-openapi.yml