Interactions between conversions and character set conversions

Character set conversions come into play at two points during message enqueue processing: during header processing, and during message body  processing. (By header processing here we mean any actual conversions of the character set  in the message header, e.g., character  set translation of personal names in addresses, not the  MIME relabelling  or other sorts of header line transformations that can also  be configured via a     mapping table.)

After the message header processing character set conversion check and before any  message body character set conversion check, the MTA consults the    mapping table (if present). If a message is to be routed to the conversion channel due to a match in the    mapping table,  then normally character set conversion for the message body during this  enqueue is disabled; it is expected instead that any relevant character  set conversion of the message body will be incorporated into the  conversion channel&#x27;s conversion script processing of the message body  parts. (The    utility may come in useful in  conversion scripts for such purposes.)   Alternatively, new in MS  6.3, the  " " keyword may be used in  channel routing entries in the   mapping table to  specify  that character set conversion of the message body (including    operations) should be performed during the enqueue to the  conversion channel (or  alternate  conversion channel) rather than being disabled as  normal at that stage. Or yet another alternative: character set conversion of the message body for messages coming from the  conversion channel may be configured, to convert the character set in  the message body after the conversion channel has performed  its operations; for such configuration, note that the    probe will not normally show the conversion  channel  as the source channel, but rather show the  "original" source channel  as the source channel.

See also:
 * Character set conversion
 * Relabelling MIME header lines
 * CHARSET-CONVERSION mapping table
 * CONVERSIONS mapping table
 * Conversion channel
 * original_channel_probe MTA Option
 * Message conversions