The Windows registry contains information about the default applications used to open various MIME types or to handle various protocols.

You may use the \mailcap file to tell Emmesmail to use this default application.

For example, the entry

text/html; DefaultApp(http) file://%s;

tells Emmesmail to use the default http client to handle the MIME type text/html, since Emmesmail replaces "DefaultApp(http)" with the complete path of the default application for the http protocol. In general, this is your default web browser.

And the entry

application/pdf; DefaultApp(EBXTransfer) file://%s;

tells Emmesmail to use the default EBXTransfer client to handle the MIME type application/pdf. In general, the default EBXTransfer client will be whatever version of Adobe Reader you are using, obviating the need to know precisely which version you have, and where it is installed on your computer.