Works:
→ Open krunner
→ Enter mail@foobar.com
→ Shows 'Launch with kmail -caption "%c" %u'

Doesn't work:
→ Open krunner
→ Enter mail@foo-bar.com
→ Shows 'Go to http://mail@foo-bar.com'

This means, as soon as the mail address contains a hyphen, the mailaddress isn't detected anymore.

It doesn't matter whether the hyphen is in the domain or the alias part of the mailaddress.

Using:
KDE 4.8.3
Qt 4.8.2