bounce message

[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.

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