efa-project.org

If I add a domain to the whitelist and leave the boxes before and after the @ blank, then it adds the entry but doesn't tag it with default. Anything entered in this way does not get whitelisted,

If I put the domain name after the @ then it works fine and if I put the word default after the @ it works fine.

Yep this is normal behavior. If you actually look at the MailScanner syntax in whitelist/blacklist text file, you'll understand the need for the word "default" or a domain to be present.