Once the system is connected to the Internet and the server is available, follow the next solutions to troubleshoot and fix the problem. They were both connected to office 365, when suddenly one day it said "updating inbox" and that's it. You should always use NTLM over Basic authentication, as Basic sends the username and password in the clear, and NTLM is Windows Authentication. On Exchange 2013, you also have a new option called Negotiate, which is recommended.

Check Disk Space

Outlook alternates between "Updating this folder" and "Trying to connect". A manual send/receive fails with a "Connection to Microsoft Exchange is unavailable message". I loaded an old mail profile for the same user account and it worked fine, when I switched back to the initial profile it started to work fine as well.

• A vast community of Microsoft Office365 users that are working together to support the product and others.
• To see if it is the same issue, open your exchange server’s event viewer and filter event 9646.
• It stores a copy of mail items on the mailbox server in the OST file on the local machine.
• After looking into it more, as the user above stated, this seems to be cache related so I nixed that on the shared box too.
• For Exchange 2013, OutlookAnywhere is a requirement and Split-DNS is Best Practice.
• Things work well for a number of days or weeks but the problem reoccurs eventually.

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If the antivirus program isn't Outlook friendly, you may experience certain issues while using Outlook. To check whether the antivirus app is preventing Outlook from updating the Inbox or Outbox folder, temporarily disable the antivirus program and restart Outlook. If the issue is resolved, exclude Outlook processes, Outlook data files, credential loop in Microsoft 365 and folder locations from your antivirus program. The SVC record had to be updated in DNS, which was the cause of the autodiscover issue in my last post.

Internet connectivity issues

This problem should only occur on the initial synchronization of a folder that is larger than 4 GB. If the folder size is initially lower than 4 GB but then grows to above 4 GB over time, you will not see this problem through normal folder synchronization. After looking into Troubleshoot Office 365 Sync and Login Issues it more, as the user above stated, this seems to be cache related so I nixed that on the shared box too. Follow these solutions to fix the Outlook stuck at updating the Inbox and Outbox folders issue. It stores a copy of mail items on the mailbox server in the OST file on the local machine. The changes made in Outlook are stored in the OST file and synchronized frequently with the mailbox server.

Check Outlook Email Account Settings

The next thing to check is the Virtual Directories and the Client Access online Outlook email repair utility Server Autodiscover URI and fix them accordingly too. All InternalUrl and ExternalUrl’s should be setup using the hostname mail.domain.com (assuming mail.domain.com is the OWA URL that you chose). You need to make sure your OutlookAnywhere and AutoDiscover settings are setup properly along with Split-DNS. OutlookAnywhere and Split-DNS are vital for future-proofing your Exchange configuration and making it work properly now, regardless if you use Exchange 2007, 2010, or 2013. For Exchange 2013, OutlookAnywhere is a requirement and Split-DNS is Best Practice.





Per the article below I updated the Ethernet drivers on the the server to the most recent version and the MTU was automatically set to 1500. Not sure why only certain machines were affected but at this point I’m keeping my fingers crossed. Turning off cached Exchange mode works, but the connection seems to be spotty as Outlook will freeze up after a while. Rebooting, deleting the OST and/or mail profile does not have any effect. Things work well for a number of days or weeks but the problem reoccurs eventually.

Outlook: featured articles

If you then allow the synchronization process to fully synchronize the folder, the status bar may eventually indicate the following text. You can set it to a higher number if you desire / need but it works for a user who has 14 mailboxes. The only other thing that I experienced was the ‘bitness’ of some outlook plugins or their application via gpo. Please provide the output from the following commands so that we can check to make sure your settings are set up correctly.



If you are running out of storage, make some space by moving some files from the storage to another folder or volume. You may also archive the OST mailbox to reduce the mailbox size. I reimaged the machine of the lone person that continued to have this problem and Outlook has been working OK for the time being. However, the problem cropped up again yesterday for a new user. The connection to Exchange drops, reconnects every few seconds or so until eventually the issue clears up. Interestingly, during this time I was unable to connect to OWA using a different mailbox on the affected client computer.