(1) A type of message that determines if a message with certain characteristics can be delivered to a specific recipient. This type of message is treated like a user message by the message transfer agent (MTA), except that it is never delivered to the recipient.
(2) A monitor that tests a transaction and then detects and reports any errors that were generated during that test.
(3) A reusable set of Java code fragments and supporting attributes for collecting detailed runtime information about objects, arguments, and exceptions. See also Probekit.