1) Next unread message.
I prefer to use a plain list view for a mailbox, and have to open a message to view it.
Remember Eudora? I used to use Eudora, and sometimes think I still should. It has this nice feature where you hit the spacebar, causing the current message to page down web-page style. When you reach the end hit that spacebar again and you jump to the next unread message in that mailbox. Nice, eh?
That does not work in Mail.
So, how about a key command to do that? Nope, not available either.
2) Invalid Email addresses.
What is so hard about telling me you can not send the email because I was too stupid to enter in a proper email address? Mail will happily harass you about opening too many windows at once.. so why not invalid email addresses?
Yeah, I caught myself BCC’ing several people, and some of them were not actual email addresses, just the domain name. Took me way too long to figure out too!