If you have more than one linkable email client installed, the Favorite Apps tab in the Preferences window allows you to select which one to use with Hookmark. That setting determines which email app is opened when you click on Hookmark’s email links, which have the form hook://email/<message-id>.
See How to Get and Use Links to Email Messages – Hookmark for a list of compatible apps, and more information on the subject of using Hookmark with email apps.
Hookmark email link handling is very flexible.
This setting does not prevent you from using Copy Link or Copy Markdown Link in other email apps. It just affects what app is used to open hook://email links.
Hookmark links to emails are not bound to any particular email app. You can switch the favorite email app setting any time.
What’s more, you can send hook://email links to anyone who has Hookmark installed, and they can use whatever email app they choose. This works for any email app that automates fetching email by RFC-compliant email ID (Outlook does not).
Your recipients don’t need to pay for Hookmark to use the email links you send them: Hookmark Basic, which is free, supports opening hook://email links.
Alternative email format : message://
Some users prefer the traditional message:// format. Therefore we have published this alternative integration script that Hookmark Pro users can apply in the Mail app:
Mail links format – Discussion & Help – Hookmark Productivity Forum.
You’d paste the script in Hookmark’s Scripts Tab – Hookmark for Mail.app.