Folder "On my Mac" does not appear on iCloud.

Leon Capart wrote:

When I receive an email that is routed to a certain folder on my Mac, it does not appear on my phone.

I know it is because on Mac Mail app, that folder appears on the left mailbox list in "On my Mac" and not in the iCloud list. So no message on the iPhone from my MacBook.

What could I do to have this folder also listed in iCloud? I want to receive those messages on my phone.

Any idea? I gave up after a few days. Calling Apple is extremely difficult from Mexico.

In Mail, anything in the ON MY MAC section is not synced with iCloud.