v52

OpenAPI 3.1.0raw.githubusercontent.com2026-07-311,1941,9384.1 MB

Email Inboxes

Add labels to an inbox message

Adds one or more mutable labels to a message. Labels carry agent workflow state such as spam, needs_review, or processed.

Labels are not the same as the send-time tags on outbound messages: tags are immutable and propagate to Email Detail Records and Mission Control for billing attribution, while labels are mailbox state that never reaches the reporting contract.

The operation is an idempotent set union — adding a label the message already carries is a no-op and still returns 200. Labels are case-sensitive, and message labels are independent of thread labels.

post/email_inboxes/{inbox_id}/messages/{message_id}/labels

Path parameters

inbox_idstring uuid required

Email inbox UUID.

message_idstring uuid required

Inbound message UUID.

Request body

labelsstring[] required

One or more labels. Each label is a freeform, case-sensitive string of at most 255 characters; a message or thread may carry at most 50 labels. The telnyx: prefix is a reserved system namespace and is rejected on customer writes.

Response

The updated message, including its current label set.