> ## Documentation Index > Fetch the complete documentation index at: https://docs.openmail.sh/llms.txt > Use this file to discover all available pages before exploring further. # Add owned domain > Register a domain your organisation controls but does not send from through OpenMail — your company's main domain, say, while your agents send from a subdomain. Once verified, recipients on it (and on any subdomain) do not count as new recipients for the cold outreach limits, so agents can write to your own staff freely. The response includes the one TXT record to publish; then call verify. Verified custom domains are covered automatically and do not need adding here. Account-wide key only. ## OpenAPI ````yaml https://api.openmail.sh/openapi.json post /v1/owned-domains openapi: 3.0.3 info: title: OpenMail API description: >- Email infrastructure API for AI agents. Create inboxes, send and receive email, and get real-time notifications via webhooks. version: 1.0.0 license: name: Proprietary servers: - url: https://api.openmail.sh security: - bearerAuth: [] tags: - name: pods description: Isolated sub-accounts for your end users or tenants - name: inboxes description: Email inboxes and their webhook configuration - name: domains description: >- Custom domains: add your own sending/receiving domain, publish DNS, and verify it - name: owned-domains description: >- Domains your organisation controls but does not send from. Prove ownership with one TXT record and mail to their addresses stops counting toward the cold outreach limits. - name: messages description: Sending and listing messages - name: threads description: Conversation threads and read status - name: attachments description: Downloading and extracting text from attachments - name: policy description: >- Correspondent policy — provider-enforced allow/block rules and allowlist mode, scoped per account, pod, or inbox. Account-wide key only. - name: limits description: >- Sending limits: today's cold outreach caps on new recipients, per account, inbox, and domain, and what raises them - name: feedback description: Reporting bugs, friction, and feature requests to the OpenMail team paths: /v1/owned-domains: post: tags: - owned-domains summary: Add owned domain description: >- Register a domain your organisation controls but does not send from through OpenMail — your company's main domain, say, while your agents send from a subdomain. Once verified, recipients on it (and on any subdomain) do not count as new recipients for the cold outreach limits, so agents can write to your own staff freely. The response includes the one TXT record to publish; then call verify. Verified custom domains are covered automatically and do not need adding here. Account-wide key only. operationId: createOwnedDomain requestBody: required: true content: application/json: schema: type: object additionalProperties: false required: - domain properties: domain: type: string minLength: 4 maxLength: 253 description: The domain to prove ownership of, e.g. `acme.com`. responses: '201': description: Domain added; publish the TXT record, then verify content: application/json: schema: description: Domain added; publish the TXT record, then verify allOf: - $ref: '#/components/schemas/OwnedDomain' '403': description: >- The key is pod- or inbox-scoped (`forbidden`), or the account already has the maximum number of owned domains (`owned_domain_limit`) content: application/json: schema: description: >- The key is pod- or inbox-scoped (`forbidden`), or the account already has the maximum number of owned domains (`owned_domain_limit`) allOf: - $ref: '#/components/schemas/Error' '409': description: You already added this domain (`domain_exists`) content: application/json: schema: description: You already added this domain (`domain_exists`) allOf: - $ref: '#/components/schemas/Error' '422': description: >- Invalid domain (`invalid_domain`), one of OpenMail's own domains (`invalid_domain_reserved`), or a public email provider nobody can own (`domain_not_ownable`) content: application/json: schema: description: >- Invalid domain (`invalid_domain`), one of OpenMail's own domains (`invalid_domain_reserved`), or a public email provider nobody can own (`domain_not_ownable`) allOf: - $ref: '#/components/schemas/Error' components: schemas: OwnedDomain: type: object additionalProperties: true properties: id: type: string description: Owned domain ID domain: type: string description: >- The domain your organisation controls, e.g. `acme.com`. Subdomains are covered too. status: type: string enum: - pending - verified - failed description: >- `pending` — added, TXT record not yet seen. `verified` — recipients on this domain are not metered as cold outreach. `failed` — the record was verified before and has since disappeared; publish it again and call verify. record: type: object description: The one TXT record to publish to prove ownership. properties: type: type: string enum: - TXT host: type: string description: Record name, e.g. `_openmail-owner.acme.com` value: type: string description: Record value, e.g. `openmail-owner=…` verifiedAt: type: string format: date-time nullable: true checkedAt: type: string format: date-time description: When the record was last looked up, whatever the result. nullable: true createdAt: type: string format: date-time Error: type: object additionalProperties: true properties: error: type: string message: type: string securitySchemes: bearerAuth: type: http scheme: bearer bearerFormat: API key ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.