Default values for this preference don't work with the current 
implementation. It has been turned into a regular preference for CVS 
HEAD/IMP 4.2, but we can't merge this to 4.1.x since the current user 
settings would get lost as a sideeffect.

The complete PHP message:
However, I now have problems reproducing it: Apparently, the setting of

$_prefs['mail_hdr'] ['value'] has no effect on the mail users I have used

for previous tests: they keep their former preference setting, even if I

- hit the "undo" link in the preference window,

- log out from imp, and in again,

- log out from imp and horde, and in again,

- stop and start the Apache server,

- delete the pertinent entry from the mysql table:

     delete  from horde_prefs

     where pref_uid='testaccount@uni-konstanz.de'

     and pref_name="identities";



The only way to reproduce the error message was to lock the entry

in horde/imp/config/prefs.php -- but then I always got that PHP warning

and was not able to find a value that would avoid it.



So the additional questions arise:

- How can I test this issue without genereating a new user-id, for every

   single test-shot?

- How can I propagate a new option (as this one) to all users of the

   previous Imp version?

- How can a user reset an option so as to use the default at run time

   (as opposed to the default at option-setting time)?

Please specify the complete error message. This should actually be 
handled gracefully in IMP.



There is no fixed syntax for textarea pref values.

For documentation on the structure of  horde/imp/prefs.dist, that file 
refers to horde/config/prefs.php. Horde/imp/prefs.dist contains 'type' 
=> 'textarea' entries, but horde/config/prefs.php  gives no syntax for 
their possible values.



An attempt with $_prefs['mail_hdr']['value'] = 
"Message-ID\nX-Spam-Level" has led to a PHP run-time error in 
horde/imp/message.php on line 340, which clearly demonstrates that 
documentation on the configuration syntax is required.



The correct syntax seems to be: "Message-ID\nX-Spam-Level\n", with 
"\n" terminating (not separating) the partial values.