If you download the Mailbox App from App Store for a free, you will be in waiting list like 300.K and probably you need to wait a long time. So i decided to dig inside this app from my Jailbroken iPhone5 and i found a way how to bypass this.
So just enable the ” orchestra.velvet.room.allowed ” with iFile from your iOS device.
The problem with login is from app itself!
Update: February 14, 2013