I have spoken to Yahoo Support on the phone several times now for a total of about 4 hours. Despite warnings of phone support being a paid service, to their credit they have not charged me for support. That said, they haven’t been much help either.
It seems clear to me that the Yahoo IMAP server is configured to sync roughly the last two weeks of messages before syncing the rest of your Inbox beginning with the oldest messages. Fine, that makes sense. Unfortunately, it doesn’t seem to give much priority to the process. It synced up to mid-2020 initially, and over the following week, has made it up to early 2023. Perhaps in another week, I might have local copies of my entire Inbox?
Going back to Yahoo Support, all they can do is tell you to remove/re-add the IMAP connection. They insist nothing is wrong with their mail system, since everything shows up properly in webmail or in the Yahoo Mail app (which is basically just webmail), and they do not think of the IMAP server as being separate from those systems. They consistently blame Apple or Microsoft or any other 3rd party mail client publisher for not syncing with their IMAP server.
As far as I can tell, upgrading to Yahoo Plus will not change anything.
