Deletemessagehash, generatemessagehash, keepmessagehash Channel Options

Message hashes
The,  , and   destination channel options control whether the MTA generates, retains, or deletes a message hash, respectively. All of these channel options first apppeared in the 6.3 release. A message hash, if present, is stored in a Message-hash: header line. is the default.

These keywords are intended to be used in conjunction with message archiving, along with message archiving MTA options, and Message Store archive options.

Note that AXS:One archiving will generate its own message hash on the messages it receives, if the MTA has not already generated and inserted such a message hash. However, in order to correlate messages in the Message Store with the messages archived by AXS:One, it is necessary that the MTA generates the hash and that that hash is retained in the messages delivered to the Message Store. Therefore, channels that deliver to the Message Store (  or    sorts of  channels) should be marked either   or (if the message hashes are being initially generated at an earlier channel stage). In contrast, a channel delivering to remote Internet hosts, such as typically the  channel, would typically be marked   even if messages going out   are being archived, since there would in general be no expectation that the remote Internet sites would do anything (get any benefit) from the message hashes.

The choice of which channel(s) to mark with  will depend upon how "soon" vs. "late" one wishes to choose to consider a message&#x27;s essential characteristics to be established. Generating a hash "early" (as soon as a message first comes into the MTA) may be before various changes (e.g., changes performed by the conversion channel) occur, or before "split up" of a message into separate copies for different classes of recipients. More "different" (in one way or another) "copies" of a message may be considered "the same" for the archival purposes when hash generation is performed "early". Whereas when hashing is performed "late" (at the final delivery channel stage), then additional sorts of differences in message "copies" can be reflected in the message hash value (more distinctions between "copies" occur). But this may be either a plus or a minus depending upon site goals.

See also:
 * Message archival and hashing MTA options
 * Message hash channel options
 * Channel options
 * Message Store archive options