Clicking an email address to "send to" launches the "New Look" Outlook 365; despite being disabled.

So, my recenlty updated Outlook 365 for desktop (online Azure tenancy) now only launches the "New Look" Outlook, when I click on an email address to "Send To". This, despite the feature being turned off in Outlook 365 (I can't stand the New Look interface); resulting in having to copy and paste email addresses into a new mail each time. Any way to disable this, so Classic Outlook just opens a new Mail when I click an address; just like it used to?