@thunderclutch I believe this is related to allowing Opera to handle mailto: links on for example gmail. i think there's something wrong here but I'm not yet sure what exactly
But just for clarity for others passing by: you do not need an extension to share links via mail in Opera on Mac, you can use the Share menu for this which is a system facility.
I understand that this post is quite old, but I wanted to share my Opera extension that does just this - https://addons.opera.com/en/extensions/details/email-this/
Email This lets you send link and complete (ad-free) web pages to your email in one-click.