On my blog at http://littlelioness.net I have the option selected to moderate comments of new commenters. I like this option, and it works well
however, it never recognises my partner as being a previous commenter on the blog, and his comments ALWAYS head into moderation. it's not too much of a hassle, but I know I trust his comments and think they should be able to appear immediately.
I have a hunch it's because he doesn't list a URL, as he has none (well he does, I set up his domain ages back but he's not done anything with it!), and it might be looking for a match there? However, he does always use the same Nickname and email address.