Sieve hold extension

The MTA supports a private " " extension action for system Sieve filters; use of this action causes the message file to be side-lined as a    file in the MTA queue area. Note that attempts to use the action in a non-system level Sieve script will be ignored without generating an error message.

As of MS 8.0.2.2, the " " action accepts an optional string argument. This argument is used to specify a reason string for the hold action; the value will appear in the  field of MTA message transaction log entries.

See also:
 * Diagnosing .HELD files
 * Sieve supported extensions
 * Sieve filters
 * log_filter MTA Option