Sieve discard and jettison actions

In addition to the standard " " action, the MTA also supports a private " " action (capability name also merely " ") which causes a "non-overridable" discard. " " is similar to " " in that it causes messages to be silently discarded. The difference between " " and " " is that unlike " ", which does nothing but cancel the implicit  " ", " " forces a " " to be performed. The behavioral difference is only relevant when multiple Sieves are involved. For example, a system-level " " can be overridden by a user Sieve explicitly specifying " ", whereas a system-level  " " will override anything done by a user Sieve.

Whether the MTA immediately discards a message upon a Sieve " " or " " action being applied, vs. routing such messages to the   channel  (for a short period of retention before being permanently deleted) may be configured via the   and   MTA options. Configuring use of the  channel allows a system administrator to, if desired, "fetch back" messages a user has very recently, mistakenly, discarded via a Sieve filter. As such,it may be useful either for debugging purposes, or for assisting users prone to setting up overly aggressive discarding via personal Sieve filters. (Technical note: When the MTA routes a discarded message to the   channel, the MTA also sets a  bit in the message envelope  that means that subsequent " " or " " actions will be ignored.  This has no effect for the discarded messages that remain in the   queue until eventually deleted from disk.  However, if instead a "retrieval" procedure is performed on such a message, such as if a system administrator moving a message from the   channel to the   channel for subsequent processing, the bit permits delivery to proceed bypassing any " " or " " actions.)

When discarded messages are deleted immediately (rather than being routed to the  channel), note that that is logged in MTA message transaction logging as if the message had been enqueued to the    channel, though in reality no such enqueue is performed and instead the  message temporary file is merely deleted from disk.

As of Messaging Server 7.0u4, the " " and " " Sieve actions now accept a single, optional string parameter. This parameter value, if specified, is logged as part of the   filter result field in the  MTA message transaction log,  assuming of course that the associated Sieve is the one that determines the disposition of the current message. Note that this argument is nonstandard; however, since the main application is in system-level Sieves, this should not present a portability problem in practice.

Note that effects similar to " " or " " may be obtained via   mapping table ,  ,  , or   flag use.

Note that application of " " will disable user-level Sieve  " " or  " "  actions that might otherwise apply. (Prior to Messaging Server 7.0.5, " " would cancel all " " actions; as of Messaging Server 7.0.5, system-level " " actions are not cancelled by " ".)

See also:
 * filter_discard MTA Option
 * filter_jettison MTA Option
 * Recipient access mapping tables
 * MTA transaction logging
 * log_filter MTA Option
 * Bitbucket channel
 * filter_discard channel
 * deliveryflags Option
 * Milter spamfilterN_config_file
 * Sieve hierarchy
 * Sieve supported extensions
 * Sieve language