How does iOS implementation of ActiveSync sync?
January 10, 2018 7:12 PM   Subscribe

When an iPhone syncs an Office 365 mailbox through ActiveSync, what elements of the mailbox does it issue a separate sync command for?

I have an iPhone that intermittently gets blocked from syncing mail with Office 365. Basically, this issue here.

I've had the issue on an iPhone X, iPhone 7, iPhone 5s and iPad Mini and on the various sub-versions of iOS 11 and 10. The mailbox is about 7GB and because everything in it needs to be available in places where there may not be connectivity, it all needs to be synced, which I'm currently doing through Push.

The Inbox and Sent Items are small and I'm not syncing the Calendar or Contacts. The rest of the mail is in subfolders. There are a lot of them but I'm not anywhere close to exceeding the Office 365 limits defined here. The Outlook iOS app appears to work fine.

When I use the iOS mail app, I can see through Powershell that it is being blocked because of Command Frequency, and I can see from the logs that the 'sync' command is the issue. What I don't understand, before I embark on rearranging the mailbox, is which particular elements are the issue. Just the currently open folder? I can consolidate some of the subfolders, but it's not clear that folders with more items will be better than more folders with fewer items.

When the iOS mail app sends a sync command, what all does it try to sync? Every message? Every folder? Some combination of the two?
posted by IanMorr to Computers & Internet
 
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