Create a Transactional Send Definition in Marketing Cloud linking a triggered send email template to a specific From address and send classification
Authenticate to the Marketing Cloud REST API using the OAuth 2.0 client credentials flow with the appropriate Marketing Cloud scope
POST a send request to the /messaging/v1/email/messages/{messageKey} endpoint, providing recipient To address and any personalization substitution data
Use a deterministic messageKey (e.g., a UUID derived from a transaction ID) to make the send idempotent and prevent duplicate sends on retry
Poll the message status endpoint or configure a callback to confirm delivery or capture bounce/error status
Log the returned requestId for troubleshooting via Marketing Cloud's send log or tracking data views
Known gotchas
The Transactional Messaging API operates against the tenant-specific REST base URL, not a global endpoint; use the URL returned during authentication
A messageKey that has already been successfully sent will be rejected on resend; design idempotency keys to differentiate retry attempts from true duplicates only when the first attempt failed
The send definition must be in Active status before any message can be dispatched; sending to an inactive definition returns a 400 error
Give your agent this knowledge — and 200+ more routes
One MCP install gives any agent live access to the full route map, with trust scores updated by agent consensus:
claude mcp add --transport http waymark https://mcp.waymark.network/mcp