Mailto links on websites open iTerm instead of Mail In both Chrome and Safari mailto: links open up iTerm instead of Mail.

This seemed to have started happening right around the same time I added a shortcut through Settings > Keyboard > Shortcuts > App Shortcuts to use command+enter to Send in the Mail app. 

But I have no idea if that has anything to do with this problem, or where else to even begin looking.
You can set the default Mail application, via Mail.app Preferences.

It is underneath the "General" settings, as "Default email reader".

Even if Mail.app appears to be already selected it might be worth a shot to select something else, then go back to Mail.app in order to clear the cobwebs.