There may also be liability when you leave the job as you're retaining copies of data that doesn't belong to you.
Not to mention that in the case of a lawsuit you might be required to give access to relevant emails. Mixing personal and professional accounts could quickly get messy.
^^^ This x1000, all of the kids starting businesses and using the cool new thing Google Apps and forwarding it to their personal Gmail account have no concept of this.
Not to mention that in the case of a lawsuit you might be required to give access to relevant emails. Mixing personal and professional accounts could quickly get messy.