Sieve mime needed MTA option

Sieve filter MTA options:  (0 or 1)
MIME message analysis is only performed when necessary and only retains necessary information. However, the serial nature of MTA operations means that subsequent operations may require additional information, forcing the MTA to analyze the message multiple times.

The  MTA option controls whether or not MIME structure and header information is retained on the first message analysis pass, even if the information is not needed immediately. A setting of 1 causes the information to be retained, 0 causes it to be discarded. The default is 1.

Saving this information may avoid having to perform another analysis pass. On the other hand, saving the information consumes memory and is wasteful when the information is not likely to be needed.

See also:
 * sieve_body_needed MTA Option