After updating to 1.7.2, and updating Mailbox to the latest version as of 12-15-14, I see the error in_array() expects parameter 2 to be array, null given with debug mode and dev mode enabled. In addition, the "Mailbox" link where the user menu is at the top is broken and results in just the background being displayed when clicked.
See: https://i.imgur.com/n8VhiD3.png
All permissions are 775 except for pluginfiles, userfiles, static, and one more folder. This is running on a Ubuntu/LAMP VPS with 2GB RAM.