+ ## The following ridiculous stunt does two important jobs. Firstly,
+ ## and more obviously, it arranges to include one more copy of each
+ ## header name than the message actually contains, thereby causing
+ ## the signature to fail if another header with the same name is
+ ## added. And secondly, and far more subtly, it also trims the
+ ## spaces from the header names so that they're in the format that
+ ## the signing machinery secretly wants.
+ dkim_sign_headers = \
+ ${sg {${map {CONF_dkim_headers : \
+ X-CONF_header_token-DKIM-Key-Publication} \
+ {$item${sg {${expand:\$h_$item:}\n} \
+ {((?:[^\n]+|\n\\s+)*)\n} \
+ {:$item}}}}} \
+ {::}{:}}