When Does the Mail App Sync Across Devices

MD_Gene wrote:

when I read an email on one device when can I expect it to show as being read on the other devices?

It's unlikely to ever be instantaneous.

First, you have to be using IMAP for your email account on all the devices.

Then it also depends on:

1. the cycle on which the server itself refreshes and
2. whether or not in Mail settings on each of your devices you have a) turned on Push and b) set Fetch New Data = Push for the email account. If Push is set, changes will sync more or less on the server's cycle. However if Fetch New Data = Fetch, changes only populate in the device when you do a manual refresh (as in swiping down in the inbox or exiting the mail app & restarting it - those actions cause a Fetch to occur).

MD_Gene wrote:

Thank you. I am a novice. How do I get to see those settings in MacOS and iOS? Thanks

In iOS, go to Settings > Mail > Accounts > Fetch New Data. Enable Push. In addition to enabling Push overall, you also have to turn it on for each account in the list below the Push toggle. And below that list, set Fetch to Automatic.

There is no real Push setting in Mac Mail. If your account is IMAP the server automatically polls your local email client on a cycle that could be a few seconds or minutes. There is, however, a Fetch setting in Mail > Preferences > General > Check for New Messages; you could set it to fetch new mail Automatically, Manually or every 1, 5, 15, 30 or 60 minutes.

I have the same issue. With two devices both with mail app open, is it intended that after deleting (for example)an email on one device, the change will only occur on the second device if the Mail app (on the second device) is closed & reopened?

Peter

Mail >> Main Menu >> Mailbox >>> sync to iCloud as per illustration below

Using 3 Apple Computers and 1 iPhone all syncing to the Same iCloud account

It just works on my machines

When you turn on the other device, open the email app, and it is connected to the Internet.