You're talking about two different emails - one is your work email, to which the workplace administrator has probably added the signature of each employee and the employee can't change it himself. To make the change, contact the administrator and, if necessary, ask him/her to change it. The other is your personal email, which you can change as much as You want because there you are the administrator. So what's weird or complicated about it? Work email is for work related emails and all other emails must go throght Your personal email account. It's also worth remembering that your work email can usually be read by anyone who has been granted the appropriate rights and authority by the workplace administration. Therefore, it is not wise to use work email for your own personal purposes. It is likely that other employees will be able to read it (or at least some of them will be able to read these emails).