Mac Mail not Syncing with Exchange email server on MacOS devices

I had a similar problem when my company moved to an exchange server. After a few days, I found out that I would read email on my mac (and move some to specific folders), but on my iPhone and iPad, those mails would still appear as unread, (and for the ones I moved, they would still be in the inbox).

I then looked at the mail using the outlook web app. What seemed to happen is that anything being done on mac mail was not reflected on the exchange mails: I would for example flag a mail on mac mail: the mail on exchange would remain un-flagged (which is why the other devices did not see the change either). But it worked fine the other way around: flagging a mail on exchange (via the outlook web app) was instantly reflected on mac mail.

To cut a long story short, the only solution that worked was to fully delete the exchange account from the mac, and recreate it.

Note that I never had an issue with receiving or sending emails: that always worked. It was just that reading mail on mac mail was not being reflected in exchange. Let's see for how long that solution lasts ...

For the avoidance of doubt - there are two problems; both of which I had.

Problem 1: suddenly mails read on MacOS Mail are no longer seen as read elsewhere; the exchange server is not updated. This only happens with an exchange server. The solution for me is to delete the whole account and reintroduce it and it works again. For a bit.

Problem 2: suddenly emails no longer arrive on MacOS Mail. This again only happens with an exchange server. The solution for this is (bizarrely!) to completely switch off your phone and/or other iOS devices. Mails arrived within minutes of me doing this.

There appears to be a cross-over: since I switched off my phone and deleted by exchange account on my MAC whilst the phone was off, then reinstating it Problem 1 has gone away completely - I had to delete my exchange account every few days up to that point.

It is broken, that's for sure.

For what it's worth, I've been on the phone with Apple technical support regarding this issue for several weeks. My rep has been extremely courteous and diligent and has spent a lot of time with me trying to resolve the issue, but it appears to be a more complex problem. I've also tried the work-arounds by other posters, including deleting and resetting your exchange account, which only works for a short while before the problem recurs. I am told Apple's engineers are aware of this issue and working on a solution, and that they still don't know if the problem originates at the exchange server or if it's an OS glitch. I will try and update this post when I hear back.

I am having the same problem.

The issue occurred just before the latest update. I updated the system, it worked and now a week later the problem occurs again.

I am also using a new iPhone 12 mini for my emails, I hope this isn't causing the issue (I doubt it).

I too have a large number of emails and am receiving 100 per day so this issue is highly frustrating.

Please can Apple sort this out.

I cannot keep shutting down and reopening my Mac every hour!

Yesterday my Mac Mail stopped syncing with Exchange (Office 365) again, 3rd time in 3 weeks. This time I did delete the account (in System prefs -> internet accts) and recreate it. Interestingly, when the inbox first appeared it was up to date... and then almost immediately it reverted back to its state just before I'd deleted the account (checking ~/Library/Mail/V7 confirmed it had deleted the account folder and made a new one). Very weird. Maybe some state token somewhere getting frozen?

Either way, Apple / Microsoft need to urgently fix this. It's hard to find words to express how bad Outlook is, and my company have disabled IMAP access so my options are limited.

All:

when reading that the Junk folder synced despite the Inbox not doing so, I tried other folders.

The Trash did not so I deleted several thousand emails on both the Mac and the server.

The Trash syncs.

Junk syncs.

Sent syncs.

Drafts syncs.

And, the Inbox syncs when deleting items.

Still, receiving mail does not sync. I am going to try culling the Inbox.

Charles

Thanks for the suggestions. I'm having the same problem with my Exchange account not showing mail in the inbox on multiple 10.15.7 devices. I also recently upgraded to iOS 14.1 on a couple of devices, but just started noticing the problem in the last day or so. I tried turning off the iOS devices, removing the mail accounts from them, to no avail. I've tried rebuilding the Exchange accounts on the MacOS devices, and that doesn't fix the problem. I find that if I choose to "Rebuild" the mailbox, the messages I've been missing pop right into the inbox, but messages sent after that action still don't show up. All the emails show up just fine in the iOS Mail application, so something changed or is wrong on the MacOS side of things. Not sure what else to try at this point.

I agree its is a reoccurring issue with the Mail app and Exchange. I had it several times in the past too but have the feeling it is triggered by large mailboxes. So what i did was:

• clean up my mail box and archive older mails locally to bring my inbox <10GB
• delete the exchange account
• delete the Exchange folders from Library/Mail (in my case the folder was V8)
• empty trash
• reboot
• reinstate the Exchange account
• wait till it has fully synced

I noticed that rebuilding and syncing takes a lot of time (indeed up to 3 days depending on the size of your inbox) during which the Mail app has its own way of syncing and not necessarily prioritizing the Inbox over subfolders. To overcome this in order to retrieve the latest mail during this period, i noticed it helps to restart mail after which the latest mail in the inbox will come in. You may need to repeat this until all mail has been synced.

Hope this helps and someone at apple also starts reading this

Moving from junk to the Inbox syncs.

After deleting Junk from Mac, the sync had some issues on the server side. It took a while so, while spinning wheel on server side, I did delete a single email in the Trash on the server and this broke the sync. It deleted the item on the Mac, but the items that had been moved from junk to Trash ij the Mac remained yet the server stopped the sync and showed nothing.

Then, deleting from the Mac inbox would sync but not from server to Mac. And, when I went to delete that email on the Mac, I received the error below.

But, I could move it to another mailbox (not with the server account).

After a bit, large moves of files on the Mac would break the sync on the server.

Having a same problem with 2 different MBPs.

Mail works for a little while after rebooting, but then it stops receiving mail to inbox (or in this case, exchange-folder where all new mail arrive). I can confirm this by comparing iPhone mail and MBP mail. folders.

HOWEVER, f.e. spam-folder is updated normally and keeps.

Quick follow-up to my post - I found a 10.13.6 machine, configured Mail with my Exchange account, and everything worked fine. I was able to receive messages in my inbox as I would expect. Those messages never show up in the inbox on the 10.15 machine until I rebuild the mailbox. As explained above, this isn't a problem on one particular machine, but all 3 of my 10.15 machines, so I don't see it as being a configuration issue. I need to track down a 10.14 machine, but this makes me think it's a problem with 10.15.7 Mail.

And of of late last night, OX X Mail on my 10.15.7 devices started syncing the inbox normally again, on all 3 of my devices! Other mail clients (Outlook, AirMail) worked fine the entire time. I didn't do anything on the machines before things started working again. At 5pm OS X Mail was still not working, and then when I checked on it 5 hours later, it was working! I was able to send and receive email immediately from my Exchange account, and messages showed up in the inbox as expected. It's still working as of this morning. I have no idea what's going on, but I don't see how it would be a problem on my end (3 different Catalina machines had the problem, 1 High Sierra machine worked fine) and multiple other clients worked just fine (AirMail, Outlook, Outlook through the web). Ughh.

I have exactly the same problem. Exchange works on my iOS devices and on my Macs using Outlook. But on my MBP2018 and 2015 iMac, exchange does not update my inbox. Other folders will sync and I can send mail but not the inbox. Sometimes restarting the mail app will help syncing the inbox, or a complete reboot of the device.

Shutting down iOS devices does not help. I also reconstructed my exchange mailbox with no success (even with deleting all ~/Library/Mail. and ~/Library/Containers/com.apple.mail folders). It looks like the mail app just randomly syncs the inbox and is sometimes (but not always) triggered by the following events: reboot the mac, restarting the mail app or checking the "acccount info" option.

Any other suggestions. Outlook is still an option but this is nit the reason i am using a Mac, it look horrible