== Indexing arbitrary mail headers
By default the Recoll mail handler only processes a subset of email headers
(+From+, +To+, +Cc+, +Date+, +Subject+). It is possible to index additional
headers by specifying them inside the 'fields' configuration file, inside
the configuration directory (typically '~/.recoll/').
Lengthy explanations are not really needed here, and I'll just show an
example (duplicated from the configuration section of the manual):
----
[prefixes]
# Index mailmytag contents (with the given prefix)
mailmytag = XMTAG
[stored]
# Store mailmytag inside the document data record (so that it can be
# displayed - as %(mailmytag) - in result lists).
mailmytag =
[mail]
# Extract the X-My-Tag mail header, and use it internally with the
# mailmytag field name
x-my-tag = mailmytag
----
Limitations:
- The mail filter will only process the first instance for a header
occurring several times.
- No decoding will take place (ie for non-ascii headers which would have
some kind of encoding).