I believe if you change the subject of the email/thread when replying, a new thread will be created. This should not be exclusive to Mail or Apple’s services, and should also work in at least Microsoft Outlook, regardless of the client (OWA or app)
Archive of download (as the main website cannot be verified/trusted as it was purposefully not renewed by the developers; someone can come along and snatch it for malicious usage, so beware): https://archive.org/download/deemix/gui
Please do hash-check with files (of the program/application) you download to ensure they have not been tampered with.
Then use an ARL (essentially a user API with premium account status):
Another tip:
In the Edit menu in Finder, hold down the ⌥ key. You will see Copy “myfile.png” change to Copy “myfile.png” as Path Name. That is how I got the keyboard shortcut.
I believe if you change the subject of the email/thread when replying, a new thread will be created. This should not be exclusive to Mail or Apple’s services, and should also work in at least Microsoft Outlook, regardless of the client (OWA or app)