What gives???

You will also notice that you can’t edit, add or remove any of the email account settings at all.

Reason for the Problem

This is caused by the sync of the backup from iTunes. The permissions on the mail folder are incorrect. The folder is supposed to be owned by “mobile”, but instead it is owned by “root”. This causes the application to crash, sending you back to the dashboard.

The Solution

The easiest fix is to run bossprefs (which you can install using Cydia), click more, and click “fix user dir permissions”. You may need to reboot.

You can also SSH into your iPhone, and take ownership of the folder directly – but this is the advanced way!