Simple Message Queue (formerly MNS) uses two identifiers to track messages: a message ID that uniquely identifies the message, and a receipt handle that authorizes delete operations.
Each message in a queue or subject has two identifiers with different scopes and purposes.
Message ID
A message ID uniquely identifies a message within its queue or subject. When a message is sent to a Simple Message Queue (formerly MNS) queue or subject, Simple Message Queue (formerly MNS) assigns a message ID and returns it in the SendMessage API response. Once assigned, the message ID cannot be changed.
Message IDs are unique only within a single queue or subject—the same ID value may appear in a different queue or subject.
Receipt handle
A receipt handle is returned alongside the message body and message ID each time a consumer receives a message. Unlike the message ID, the receipt handle is tied to the receive action, not the message itself. To delete the message, use the receipt handle—not the message ID—within the validity period.