Sieve warn extension

As of the 8.0 release, warnings that occur during Sieve evaluation (such as memcache protocol issues and issues with the duplicate or  vacation extensions) will result in a " " clause in the    field of MTA message transaction log entries.

Additionally, as of 8.0 the " " action, which takes either a string or list as an argument, is available for system-level Sieve scripts;  its argument will be included in the " " clause in the    field. This nonstandard extension is available without any special capability declaration; no " " action is needed for its use.

New in MS 8.1.0.3, the private Sieve environment item,, allows scripts to check and see if any Sieve warnings have occurred. The operation only succeeds if one or more warnings have occurred since the last check of  - or if no previous calls have been made, since the start of script processing. The item return value is the text of those warnings.

See also:
 * MTA transaction logging
 * log_filter MTA Option
 * Sieve duplicate extension
 * Sieve vacation extension
 * Sieve hierarchy
 * Sieve supported extensions