.MSPX File Extension
File TypeMicrosoft ASP.NET Web Page
File format categories include Binary, Text, XML, and Zip. The format of this file type has not been determined.
What is an MSPX file?
Web page developed using Microsoft's presentation framework for ASP.NET; processed by a Microsoft Internet Information Services (IIS) Web server; dynamically generates content that is passed to the client's Web browser.
MSPX Web pages are similar to .ASPX pages, but use ".mspx" as an alternative extension.