The Mail System in WoWmod is where you are able to do your trading, selling and buying. And also transferring materials between your characters.
You use the mail by typing wcmenu - Press 1 to get into the Items menu - Press 5 to open the Mail menu - Press 1 to write new mail. Here you type in the CharacterID for the Character you want to transfer to. NOT the PlayerID! If you press 2 instead of 1 in the Mail menu you get to the Inbox, where you can see all your mail. You need to press the number behind the item in the mail to move it to your inventory. After you have moved everything in the mail to your inventory, it is recommended that you delete the mail. If not, you will get warnings about there being mail in your inbox.