iCloud Mail Read/Unread Sync

Long time listener, first time poster!

My mail setup is pretty straight forward. I have work mail via Exchange (Office 365). I then have my personal domain hosted on Fastmail which I use for personal account. For everything else such as all online accounts etc I have been using a Gmail account for years. I decided that since I am all iOS I should just use iCloud mail for that stuff, especially since sign in with apple option was announced.

Here is the issue. For my Exchange and Fastmail account if I read something on my Mac it shows as read immediately on my phone. This is not the case with the iCloud account. Fastmail uses IMAP so I can’t figure out why iCloud is not doing the same? Is anyone else having this issue, or is my setup wrong somewhere?

Thanks! That is the same behavior I am seeing. I just assumed it would do a better job of this given that it is Apple’s property.