PowerShell to set New UPN, Primary and Secondary Proxy Addresses on the Active Directory.
For Single User For bulk Users. CSV File Format Username PrimarySMTP SecondarySMTP NewUPNSuffix jdoe jdoe@prismtp.com jdoe@secsmtp.com newdomain.com asmith asmith@prismtp.com asmith@secsmtp.com newdomain.com