[common] What data (a piece of email or netnews, or a stream of TCP/IP packets) has fallen into if it disappears mysteriously between its origin and destination sites (that is, without returning a {bounce message}). "I think there's a black hole at foovax!" conveys suspicion that site foovax has been dropping a lot of stuff on the floor lately (see {drop on the floor}). The implied metaphor of email as interstellar travel is interesting in itself. Readily verbed as blackhole: "That router is blackholing IDP packets." Compare {bit bucket} and see {RBL}.
[glossary]
[Reference(s) to this entry by made by: {bit bucket}{drop on the floor}]