I havent used outlook 2007 but I used 2003 and I dont think you can get it to switch automatically if one account goes down. I think you will have to do that manually.
its only a guess since I havent used 2007 but to switch to another account to send the automatic email you will have to switch to that account by manually doing it or creating a script to do it and I am no script writer either.Thanks for your reply .u mean to say only programatically i can achieve this ?.