Maxprocchars Channel Option

Specify maximum length header line that the MTA will rewrite
Processing of long header lines containing lots of addresses can consume significant system resources. (Note, however, that resource consumption is much reduced in PMDF V5.0 as compared with previous versions of PMDF.) The  source channel option is  used to specify the maximum length header line that the MTA will process and rewrite. Messages with header lines longer than this are still accepted and delivered; the only difference is that the long header lines are not rewritten in any way. A single integer argument is required. The default is to process header lines of any length.

See also:
 * Message size MTA options
 * Long address lists or headers channel options
 * Channel options