Name:   phil - Subject:   microsoft outlook HELP Date:   5/30/2017 9:17:32 AM (updated 5/30/2017 9:30:26 AM)

What version of outlook 2003, 2007, 2010, 2016 or is Office365?

The one thing Microsoft is good at is breaking a good thing.

Did microsoft install any updates to your office / outlook since the last time it worked correctly.  if so uninstall to see if the problem goes away.

 Take a look here, if you have to ask what the registry is and why back it up before modifications, The page references a fixit download but as usual their page is like GFY, missing the important parts.

https://support.microsoft.com/en-us/help/813745/-either-there-is-no-default-mail-client-or-the-current-mail-client-cannot-fulfill-the-messaging-request-error-message-when-you-send-e-mail-from-third-party-program-in-outlook

As a last ditch possibility some have reported success resolving the error with adding another email program ( Thunderbird ) setting it as default and then switching back later.

Ignore GFY his thermostat is stuck on stupid.