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Outlook’s ability to connect to the mail server may be blocked by firewalls or antivirus software. After you’re satisfied, turn off your firewall or antivirus program for a while. If it does, clear Outlook credentials manager you might need to include Outlook exceptions in the settings of your security program. The sync will fail if the groups you selected to load users from no longer exist in Azure AD.
Methods to fix Microsoft Outlook syncing error
Tempted to create a Test Shared Mailbox, but thinking that wouldn't be an accurate test for inbound mail, etc. or just actually tested by the Users at all.There are various methods to resolve the Outlook sync issues, including manual and third-party solutions.The sync does not delete users but rather sets them to inactive.These are the only two I've seen have this issue and I was wondering if you've seen this and figured out a 'fix'?If that doesn't resolve your missing users issue, please follow our guide to troubleshooting missing users below.This software also has a splitter option to split large-sized PST files into smaller ones, helping users prevent oversized PST file issues.Another which is shown below, is a user opens a new message, or replies to one, and lets it sit for a while.I have a couple of Users and a Shared Mailbox that were migrated and both Users are experiencing issues with the Shared Mailbox updating on a regular basis.
Similarly you should review the Users Deactivated sheet on the sync summary spreadsheet attachment as you can also delete these users to bring your total down. I have multiple users experiencing sync errors with Outlook and office365. Another which is shown below, is a user opens a new message, or replies to one, and lets it sit for a while. When they go back to the message and press send they get an error that the message has been deleted. Ive repaired the OST and changed cache mode to only cache 1 year. The M365 sync establishes a synced dataset based on your M365 data and the filtering configuration of your sync.
Common Causes of Sync Issues in Outlook
Before finding solutions, we suggest that users check their internet connection. Sometimes, Outlook sync issues can arise because of poor internet connection. If you are still facing this issue, kindly follow the solutions below to fix the sync issues in Outlook. There are various methods to resolve the Outlook sync issues, including manual and third-party solutions. Now, let us start with the manual processes to fix Outlook syncing errors.
[Answered] Secured OST to PST Converter for OST to PST Conversion
So, follow the below steps to reset Microsoft Outlook settings. The sync does not delete users but rather sets them to inactive. The idea is to provide a recycle bin of users who you can delete when you no longer need them. You can view your inactive users on troubleshoot Outlook synchronizing folders error the Users page and delete them as you see fit.
What should I do if my sync failed due to authentication issues?
But setup is a little complicated and it can sometimes be difficult to identify the source of problems. We have resources to help you identify potential issues and fix them. The Support and Recovery Assistant, a tool provided by Microsoft, can identify and resolve common Outlook problems. It is capable of automatically identifying problems with account setups, sync, and Fix Outlook and Office 365 Errors 2025 other typical mistakes.
Typically this is because the selected groups have been deleted from Azure AD since the M365 sync was configured on your account. After viewing, see fixing problems with directory synchronization for Microsoft 365 to correct any identified issues. There can be several reasons for the Outlook synchronization error. Before we know the solutions, we will understand a few common causes of the Outlook sync problem. To get the sync working you will either need to delete users or have the user limit on your account increased. If you don't wish an inactive user to be made active by the M365 sync, you can add the user's email address to the sync forbid list.
It is possible for a corrupted Outlook profile to impede synchronization. After these instructions, ensure the sync settings are correct and check everything is working well. This means that the authentication setup for your sync is no longer valid.
Use the Microsoft Support and Recovery Assistant
The sync will fail if it can't find any users that comply with your filtering preferences or the system's requirements for user records. The system requires that users have a first name, last name and a valid email address that conforms with your domain lock if enabled. The most common reason for missing users is that you've run a Test Sync, instead of a Manual Sync. If that doesn't resolve your missing users issue, please follow our guide to troubleshooting missing users below. With directory synchronization, you can continue to manage users and groups on-premises and synchronize additions, deletions, and changes to the cloud.