Change Default Email

Hi, I'm trying change my default email account from Gmail to Yahoo. I've followed the Apple procedure for this topic. In the General tab, my yahoo a/c doesn't appear in the Default email reader popup menu. I can confirm that my Yahoo account has been added in my System Preferences, Internet Accounts...

I've designed a system for my business where I want to email customers from Numbers spreadsheets, so I really need to get this sorted. I know I can do a workaround but don't want to do that...