Hello,
The email addresses people enter for their wiki accounts are verified with inc/EmailAddressValidator.php, which is too strict: it refuses perfectly valid email addresses such as <webmaster@localhost> (which is a kind of good default for the wiki administrator). This was reported in Debian:
http://bugs.debian.org/594732 .
Here is a patch to correct that. If you wish, you can also pull the branch contrib/soften-email-validator from <git://git.ortolo.eu/pkg-dokuwiki.git>:
$ git pull
git://git.ortolo.eu/pkg-dokuwiki.git contrib/soften-email-validator
Regards,
--
Tanguy Ortolo
Maintainer of the Debian package