• don't use an extra field for domain, just check the config option
• don't allow empty emails when signing up even if we allow them in general

git-svn-id: http://mantisbt.svn.sourceforge.net/svnroot/mantisbt/trunk@1443 <a class="text" href="/?p=mantisbt.git;a=object;h=f5dc347c">f5dc347c</a>-c33d-0410-90a0-b07cc1902cb9