Inner, noinner, sourceinner, nosourceinner Channel Options

Inner header rewriting
The MTA only interprets the contents of header lines when necessary. However, MIME messages can contain multiple sets of message headers as a result of the ability to imbed messages within messages (message/rfc822). The MTA normally only interprets and rewrites the outermost set of message headers. The MTA can optionally be told to apply header rewriting to inner headers within the message as well.

This behavior is controlled by the use of the  and   channel options on destination channels and/or the    and (new in 8.1.0.1)   channel options on source channels. and/or  tells the MTA there is no special need to rewrite inner message header lines (though inner message header line processing may be triggered by other MTA facilities). It is the default. , when placed on a destination channel, or, when placed on a source channel, tells the MTA to parse messages and rewrite inner headers.

These options can be applied to any channel.

See also:
 * Headers channel options
 * Attachments and MIME processing channel options
 * Channel options