A facility is described for managing parallel requests in a communications environment having devices or applications ("request handlers") that support serial and parallel message processing. In various embodiments, the facility receives messages directed to a recipient from an application and sends a first message to the recipient without sending subsequently received messages to the recipient. Upon receiving a response from the recipient to the first message, the facility determines whether the recipient supports parallel or serial message processing. When the recipient supports parallel message processing, the facility sends the subsequently received messages to the recipient without awaiting a response to a message before sending another message. When the recipient supports serial message processing, the facility sends a subsequent message after receiving a response to a previously sent message.