If "support@yourdomain.com" internally is sent to timcook@apple.com, people will know. If it's sent to nickphx+support@fastmail.com, your personal email address

If "support@yourdomain.com" internally is sent to timcook@apple.com, people will know. If it's sent to nickphx+support@fastmail.com, your personal email address, name, and login are leaked.