Though you are most likely correct, for completeness, please check the
archived item with the '99' date and make sure it does say 1999.

Though I have not checked the current version+ of LISTSERV search, I have
noticed that if a SEARCH is done with a "SINCE TODAY" it will
occassionally return those items that were post-dated with an RFC822
DATE: field way into the future.  I.e., it doesn't use true
archived-at-the-server date, but "user" supplied.

/Pete