I had the mail issue last night when I jailbroke using the new modmyifone, GUI, everything worked perfect, so if anyone wants, I can say it was easy and it worked. YouTube works perfect to btw. To fix the mail issue, SSH into your phone, var/mobile/library/mail Delete this mail folder, and wait a few seconds, then go add a mail account by opening mail. This worked for me. Be sure to back up the folder before though. (You should always backup any folder your deleting or changing. I learned this the hard way with springboard.app) This fix worked for me. Mail no longer crashes, runs smoothly, and I can add and delete accounts with ease. Once you do this, you can either sync with iTunes, or just manually add. I went manual. Hope this helps someone!