Sieve conversiontag extensions

For system-level Sieve scripts, the MTA&#x27;s private conversion tag manipulation Sieve actions " " and " " have been supported since MS 6.3, and the " " action has been supported since Messaging Server 7.0u3. No capability name (no " ") clause need be used before using these actions. These actions take a single argument specifying either a string or list of conversion tags. " " adds the specified conversion tag(s) to the current list of conversion tags, while " " empties the existing list before adding the specified new conversion tags. Note that these actions are performed very "late in the game" of message processing, so " " can be used to undo all other converison tag setting mechanisms. " " can be used to undo all or part of preceeding " " or " " operations.

Also, in system-level Sieves, as of MS 6.3, the " " test accepts  " " as a field specifier value,  checking the current list of conversion tags, one at a time. (This test only "sees" the set of conversion tags that were present prior to Sieve processing; the effects of " " and " " are not visible.)

For further discussion and examples of using Sieve conversion tag extensions, see Sieve filter manipulation of conversion tags.

See also:
 * Conversion tags
 * Sieve filter manipulation of conversion tags
 * Sieve envelope extension
 * Sieve hierarchy
 * Sieve filters
 * Sieve supported extensions