Can an agent send an email with Customer.io Transactional Messaging?
Who does each step
Whether the agent handles it alone or a person has to step in.
- 01
Discover
MachineThe vendor's machine-readable docs show the agent where and how to call this job.
- 02
Access
Workaround · setupYou give the agent a key or token.
- 03
Onboard
Workaround · setupYou sign up or register a client for the agent.
- 04
Pay
Workaround · setupYou add a payment card at the vendor's checkout.
- 05
Confirm
MachineThe response or specification defines errors the agent can distinguish from success.
- 06
Sustain
Workaround · setupYou replace or revoke the agent's access when it needs to change.
- Access: handing over a key or token.
- Onboard: signing up or registering a client for the agent.
- Pay: adding a payment card.
- Sustain: renewing, replacing or revoking its access.
To remove these handoffs: support OAuth client registration so the agent can register its own client and ask for consent; provide an agent registration route, such as auth.md, a sign-up API or OAuth client registration; support payment in the request, such as x402 or MPP, so setup does not require a person to add a card; provide key management or OAuth refresh and revocation so the agent can maintain its own access.
Agent surfaces
The probe
Each request it sent and what came back; the descriptors it read, counted, with what they named.
Discover30 descriptor reads9 facts
- Found
- API catalogdocs.customer.io/integrations/api/customerio-apisAPI catalogdocs.customer.io/ai/mcp/MCPmcp.customer.io/mcpMCPmcp-eu.customer.io/mcpFor agentscustomer.io/auth.mdFor agentscustomer.io/llms.txtFor agentsdocs.customer.io/llms.txtFor agentsapi.customer.ioSkillscustomer.io/.well-known/agent-skills/using-customer-io/SKILL.md
- From
- customer.io/.well-known/api-catalog · customer.io/.well-known/mcp/server-card.json · customer.io/auth.md · customer.io/llms.txt · docs.customer.io/llms.txt · customer.io/.well-known/agent-skills/index.json
- This endpoint
- api.customer.io is named by a document written for agents
Job requestPOST api.customer.io/v1/send/email40151 ms
- Request
- POST https://api.customer.io/v1/send/email
- Response
- 401 · application/json · 56 bytes
- Body
- sha256:6d4634fe4f43bb7e82c53e686c4e9af2530e0e8927f863b4035315b79ed646ad
- Exchange
- sha256:383e5f7142d2617805082551a31caedc5af03dd4faade5b329bd3346e5974013
Resource metadataGET api.customer.io/.well-known/oauth-protected-resource/v1/send/email40464 ms
- Request
- GET https://api.customer.io/.well-known/oauth-protected-resource/v1/send/email
- Response
- 404 · text/plain · 19 bytes
- Body
- sha256:b16e15764b8bc06c5c3f9f19bc8b99fa48e7894aa5a6ccdad65da49bbf564793
- Exchange
- sha256:a90e958b74fe290e1e20cc584a1cb7e7520f02d4ff580acab1450157e4e85536
Resource metadataGET api.customer.io/.well-known/oauth-protected-resource40466 ms
- Request
- GET https://api.customer.io/.well-known/oauth-protected-resource
- Response
- 404 · text/plain · 19 bytes
- Body
- sha256:b16e15764b8bc06c5c3f9f19bc8b99fa48e7894aa5a6ccdad65da49bbf564793
- Exchange
- sha256:750bba534112a736e854f3b3d8c57d8e370293b61974294350d9a10356987eb0
Declared pageGET customer.io/signup/30847 ms
- Request
- GET https://customer.io/signup/
- Response
- 308 · application/json · 0 bytes
- Body
- sha256:e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855
- Exchange
- sha256:ecb8978e0a442478075bf80c29163419198916791b9208679b887bfbd8ccff7c
Declared pageGET fly.customer.io/settings/billing/your-plan20068 ms
- Request
- GET https://fly.customer.io/settings/billing/your-plan
- Response
- 200 · text/html · 21312 bytes
- Body
- sha256:f5c133d12c0d219adf95203dc7d6ceb048b361e4d427c8006e85a77701958e6e
- Exchange
- sha256:dfa6cc9b43e56cffbe91161f43645a546acc3a2b44aa8b802c62dd161ba25942
Customer.io on the startup-offers board
- Up to 12 months free, up to 12 months freeCustomer.io Startup Program
The grade’s badge
One image that keeps itself current, linking here.
[](https://sourcey.com/c/customer-io/agent-readiness/customer-io-transactional-messaging/email-send)Improve the report
Correct it, probe it again, or improve the path.
- Profile
- arp_01m4t8d81dtfc8b1c0s45a80pb
- Projection
- sha256:abb3cc16080b1d8468d73ad5fe1fbdc3dff5712e6871f7ce54dd8712fb9b3860
- Policy
- kind-2026-10-12.2 · sha256:b612172aad277b54461de84e006815126f2df566563954b02f4432a39cad89ac
A report or a reassessment request names this profile, its revision and its projection. How report cards are assessed →View the exact declaration