How to know which is the default mail client?

Question

When my application starts, I want to know if Outlook is installed and whether it is the default mail client.

For installation i just check a registry key, but how to know if it is the default mail client?

Answer 1

According to this MSDN link "HKEY_LOCAL_MACHINE\SOFTWARE\Clients\Mail can contain zero or more subkeys, one for each registered email application".

Regarding which of the registered e-mail apps is the default one, the same link says that:

HKEY_CURRENT_USER\SOFTWARE\Clients\Mail\(default)

will give you the default mail app for the current user (if it is set), while

HKEY_LOCAL_SOFTWARE\SOFTWARE\Clients\Mail\(default)

gives you the system-wide one.

The link also states also that it is not the same having the mail client registered as Start menu mail application, as the system default email client or the registered mailto handler (which seems a bit odd imho).

The information in that link applies to XP, Vista and Win 7.

HTH