"The Sieve scripting language allows users to control handling and disposal of their incoming e-mail. By default@ an e-mail message that is processed by a Sieve script is saved in the owner's ""inbox"". Actions such as ""fileinto"" and ""redirect"" cancel this default behavior. This document defines a new keyword parameter@ "":copy""@ to be used with the Sieve ""fileinto"" and ""redirect"" actions. Adding "":copy"" to an action suppresses cancellation of the default ""inbox"" save. It allows users to add commands to an existing script without changing the meaning of the rest of the script."
RFC 3894-2004 history
2004RFC 3894-2004 Sieve Extension: Copying Without Side Effects