is there an addon that lists the contents of the mailbox like it does in the bank/inventory? and you can rightclick on the stuff saying "send to xxx" or something like that?
I can help with the listing part, I use a mod called "Possessions" that can be found on this site at http://www.wowinterface.com/download....2Updated.html . Now it hasn't been updated since December of last year, but it's still working just fine for me. I love the mod because it remembers all the inventory on all my toons, whether it's in their bags, the bank or the mail. Give it a try and see if it helps you with some of what you're wanting. I don't know of anything though that can help with that other part of being able to just "send to xxx" by right clicking.
BankItems keeps track of gbank/bank/bags/mail and even the items your character is wearing (on all your toons), but no rightclicking to send mail afaik, but then again it's not a mail addon