Sierra Mail does not sync with my Exchange server anymore.

Just bought a new Mac to replace my 2008 Mac Pro. Copied all my stuff across, updated everything and looked forward to a pleasurable experience. First thing to fail was Safari. I ended up disabling a security system provided by my bank called Rapport. This got Safari working. Chrome and Firefox both worked without disabling Rapport, so this was already a bad sign. Also took a while to find that out, luck more than analysis but if anyone else has had these problems this might be helpful?

Mail synched with my gmail accounts but not with my work Exchange account. My laptop has an up to date Sierra OS and synchs fine. I can use the web mail system through Safari so my password is correct etc.. Still no mail synch with Exchange. I would have thought that fixing this would be a fairly high priority for Apple as it seems to affect quite a few people.

Trusteer Rapport is a known troublemaker on both macOS and Windows. It's garbage. Don't blame Apple for bad 3rd party software.

As for you Exchange account, what did the IT people at your office say when you told them about it?

Trusteer Rapport deleted from all my machines. Still no synch with my Exchange server. Will go to see IT support tomorrow. It might be a quirk with Exchange, but with 2 machines synching and one new one not I am confused as to what to try next. IT support may well have logs of what I've been doing. Same edition of Mail on 2 of my machines, so again no clear evidence of anything yet. At the moment although Rapport is clearly guilty of clobbering Safari, it does look like an Apple fault with mail at the moment, but not prepared to commit blame to anyone yet until I have established what has actually happened. Rapport has been eliminated and there is still a fault.

Still no synch with my Exchange server.

There have been changes in how Mail stores it's data from previous versions of macOS. I'm not sure how you brought your data over to the new Mac, but the upgrade process could be at fault with your sync issues.

If you did not migrate your previous Mail data over, remove the Exchange account and add it back.

If you did use migration, let's look into the User's Library/Mail folder.**

Sierra stores your mail in V4. Do you see V2 of V3 folders? El Capitan used V3, previous versions macOS used V2. If yes, is there anything in these folders except MailData folder? If no, delete these folders.

Next, look in the V4 folder. You should see something similar to this:

(Note: each account will have it's own folder and the "On My Mac" folders will also have it's own folder. This example is for one account and the "On My Mac" folders)

C7AA1753-CDA7-4C5D-9505-05B73B565A50/

C9A984AA-A145-4988-8279-B93445951DAB/

MailData

Look in the alphanumeric folders to locate your Exchange account. With Mail quit, delete the Exchange alphanumeric folder.

In MailData folder, delete the three files with envelope in the name.

Log out under the Apple in the Menu bar.

Log in and empty the trash.

Open Mail. Mail will reindex your data.

When indexing is complete, Mail will open and should start the Exchange download again.

Let me know if this helps.

**Show User's Library

The User's Library folder is hidden by default. To unhide: Select the Finder in the Dock. Under Go in the Menu bar > hold down the Option key and you’ll see the Library.

Finding the User Library Folder

http://www.takecontrolbooks.com/resources/0167/site/chap11.html#FindingtheUserLi braryFolder

Brilliant!! Many thanks. It would be nice to offer you a "virtual drink" as a thank you but I guess not a real one. A bit apprehensive at first as many things could have gone so wrong. However, once I had confidently identified the right folders etc. and followed the instructions all came back to sync properly. I had a V2 folder, just for interest. Its gone. Everything else has magically appeared in the right place. My early 2008 Mac pro can now rest in peace. It was a good machine and owes me nothing. My little (outside) Mac mini is now happily processing my stuff. Its got a terabyte of SSD so its not that small on the inside, nice machine now.

Many thanks once again!

Guys, I'm going to save you all a lot of grief. Irony of ironies I couldn't sign in to discussions with Safari post Mavericks upgrade to Sierra. However, IE is successful in Windows for those experiencing the same. Okay, caveats, 1. restricted to MS Exchange 2016 so can't say it isn't current, 2. MacOS Sierra post Mavericks upgrade on MBP, bad idea BTW as I expected, 3. I don't use Mac Mail but MS Outlook 2011; can't wait for the fiasco with 2016. However, this problem will likely affect anyone using mail, calendars and contacts. I use the latter to keep my local address book in sync with my Exchange contacts.

Issue: can't authenticate using Exchange Web Services although all my iDevices are fine (they use Exchange Active-Sync). Many of you are experiencing what you believe is a Mail issue; it is in part.

In short, since I'm the mail admin for my Exchange organization, I have latitude. This issue is a consequence of Mac Mail using "Basic Authentication" to access EWS. Current Exchange Best Practices don't enable it by default. It uses NTLM authentication which coincidentally functioned for me in Mavericks for Contacts and I assume would have for Mail and Calendar as well prior to my Sierra upgrade.

There are two solutions:

1. Have your Exchange mail administrator enable Basic Authentication on the EWS web service in IIS (I'm running Exchange 2016) and require SSL encryption. For security reasons this isn't my preferred choice. I would rather the Apple authentication API use NTLM but **** may freeze over first.

2. All the suggestions about manual setup follow with this exception, for External and Internal urls set them to the internal Exchange server host and DON'T use SSL; this only works on your LAN where you have direct access to the mail server (i.e. no firewalls, etc). For example:

Internal URL: http://yourExchangeHost.internal.net/EWS/Exchange.asmx

External URL: http://yourExchangeHost.internal.net/EWS/Exchange.asmx

Again, option 2 is equally terrible but I trust my network and can live without it when I'm external to it.

I hope the helps some of you pulling your hair out.

These settings did not work for me on the latest version of Sierra, however another solution did work:

1) Similar startup to Mynet post: System Preferences, Internet Accounts, + add account, Exchange;

2) Enter bogus info into the first dialog (email, pass, etc = temp);

3) At second dialog enter correct email address, use the same email address for the user name, and use outlook.office365.com as both Internal and External URLs.

Process proceeded normally from that point forward.

A

I have the same problems! I am still using OS Sierra 10.12.6! The problem started when I was told that my head office upgraded their Exchange Server to Exchange Server 2016 which uses HTTP2 Protocol! It seems that Apple has recognized (not sure about that) that Apple mail is not compatible with HTTP2 Protocol! I am trying to call all over the place to get a reply from Apple but so far without success!

I have Microsoft Office Outlook for Mac and I can sign in without any issues. However, I am having the same issue with authenticating Exchange accounts in Apple Mail. I just upgraded to 10.13 and now I cannot connect to Exchange.

I know it doesn't solve the problem with Mail.app in High Sierra, but Spark by Readdle (free on the app store) works with our Exchange 10 server. I will keep the account active in Mail so that if it starts working again, I'll know about it.

Strangely, I have no problems (and have never had any problems) with the Mail app on iOS 11. Go figure.

/Bill

Been on same boat for a while now, just find the Spark is not even close to the convenience of using OSX mail, while what a conundrum that Microsoft has put us in. Another day, another nuisance from them, life lives on...

We just recently upgraded from Exchange 2013 to 2016, and now the problems started. I did what you recommended viz deleted the old account and added it as new. I also put in the external and internal URLs (the same for us). However, the problem persists.

Some iPhones too are having issues, like messages sitting forever in outbox. I checked the quotas, deleted the account and re-added but still the same problem.

Any suggestion is welcome. Thanks.

Use Outlook until Mail fixes the problem in an update.

You need to report it to Apple Feedback so it can be logged and put in the queue to be fixed.

https://www.apple.com/feedback/

Works just fine for me on multiple Macs running Sierra. Contact your IT department.