@Bilbo63 Is Mail.app definitely set as your default Mail client?
It could be that you didn't allow access for Alfred to control Mail.app when macOS popped up the dialog to ask for permissions (it only ever does this once, the first time Alfred needs access). Could you open macOS Preferences > Security & Privacy > Privacy > Automation, and ensure that "Mail" is selected for Alfred 3?
Also, what happens when you use the 'email' command inside of Alfred.
