I have TB running all the time and checking two accounts every 10 minutes. Then it processes some of the incoming mail automatically.
To be able to check the accounts, they must be unlocked - and if so, the account properties can be accessed by anyone having a physical access to the machine. Then you can retrieve the password for an unlocked account in seconds with a tool like Revelation from snadboy.com

Is there any way to have TB running all the time, and keep the login info secure?