Show error message if sent-mail folder and drafts folder of an identity doesn't exist anymore.
Show error message if sent-mail folder and drafts folder of an identity doesn't exist anymore.

svn path=/trunk/kdenetwork/kmail/; revision=169855

lefou/kdepim-noakonadi,lefou/kdepim-noakonadi,lefou/kdepim-noakonadi,lefou/kdepim-noakonadi,lefou/kdepim-noakonadi,lefou/kdepim-noakonadi