With the ABL–JMS API, an incoming message is acknowledged automatically when the message handler finishes execution. Acknowledgement is sent on the request for the next message, improving performance.

A client or communication failure between the time the message handler finishes execution and the time the ABL–JMS implementation sends the acknowledgement can result in the messages being redelivered (according to the JMS message redelivery rules). An application can use a transacted session to avoid this message redelivery problem.

Unlike Java–JMS, the ABL–JMS API does not support the explicit acknowledgement of messages or the "lazy" acknowledgement of messages (the JMS CLIENT_ACKNOWLEDGE and DUPS_OK_ACKNOWLEDGE modes).