bounce message n.
[common] Notification message returned to sender by a site
unable to relay email to the intended
Internet address
recipient or the next link in a bang
path (see bounce, sense 1).
Reasons might include a nonexistent or misspelled username or a
down relay site. Bounce messages can
themselves fail, with occasionally ugly results; see sorcerer's apprentice
mode and software
laser. The terms `bounce mail' and `barfmail' are also
common.