Enable sieve ereject MTA option

Sieve language extension MTA options:  (0-2)
(New in 7.2-7.02.) The  Sieve " " extension  defined in RFC 5429 is designed to be used to reject spam. Because of this it is only supposed to be available on ingress MTAs capable of returning an SMTP level error directly to a remote systems in other administrative domains. Ereject is not supposed to be available on internal MTAs incapable of sending a direct SMTP response because it&#x27;s use on such systems can produce blowback spam.

The  option provides the means to disable " " on internal systems. A value of 1, the default, enables the use of " " in all scripts. A value of 0 disables it; when  is set, a Sieve script statement of &#x27; &#x27; will be ignored.

See also:
 * Sieve filters
 * Sieve ereject and reject and refuse extensions
 * Sieve language extension MTA options