GF wrote :
IS there any way for doing what I need (apart
modifying brutally the
specialPreferences.php?
I would suggest to add the appropriate Hook (
http://www.mediawiki.org/wiki/Hook) in
LocalSettings.php.
Someone with more experience with hooks and SpecialPreferences.php might tell you which
hook to use.
my guess would be the "InitPreferencesForm" Hook (with something like
$foo->mUserEmail = $wgUser->getEmail(); )