Adding email to button to actually work

Hi everyone!

I used to be able to add a button and click the "email" on the drop down and type in an email so when someone clicked on said button, it would open outlook and autofill who to send email to.

Then, the functionality changed and I started having to put "mailto:" in front of the email address for it to populate.

Now, I can't get it to work. Anyone know what to do?

Thanks!