Do I have the right to my preferred name on email and company website?

My new employer uses first initial last name for email address and first name last name as the display name. I am known by my middle name, and have not used my first name personally or professionally my entire adult life. I presented my full name on my application documents and résumé, but made my preferred name known during the process leading to employment. When they contacted with information about accessing my new work email, I immediately got back to them asking they change the user ID and display name to reflect the name I use. They have refused, claiming that they are using my legal name, and they do it this way for everybody. This name issue is not just email; it permeates the entire digital environment. My position requires frequent contact and interaction with people inside and outside the organization. They brush aside my concern that the mismatch between the name I use and the name that is in the directory and on email will create confusion or difficulty contacting me. They are completely dismissive of the personal impact of unilaterally forcing an unwanted an unnecessary name change. What are my rights, and what are my options?