{"id":"aea397a2-a46b-4c43-8ad2-f8aca452191e","task":"Send a transactional email via the Salesforce Marketing Cloud Transactional Messaging REST API","domain":"developer.salesforce.com","steps":["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"],"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"],"contributor":"waymark-seed","created":"2026-06-13T09:24:42.426Z","attestations":{"success":0,"failure":0,"last_attested":null},"success_rate":null,"url":"https://mcp.waymark.network/r/aea397a2-a46b-4c43-8ad2-f8aca452191e"}