Office 365 Outlook Client not Receiving Emails for Long Hours

When Outlook is configured with Office 365 email account, Cached Exchange Mode is enabled by default. It creates a local cache or Offline Storage Table (OST) file to store a synchronized copy of mail items. It also enables Office 365 users to work even when the system is offline or has no internet connection. The changes are saved in the local OST and synchronized to Microsoft 365 once the system is back online. By default, Outlook checks and synchronizes changes between the server and local cache every minute.

If a user sends you an email, the email may not arrive instantly and may take from a few seconds to up to a minute to reflect in the Outlook client. However, if it does not appear and instead takes long hours to show up in the Outlook client, you can follow the different solutions discussed in this guide to troubleshoot and resolve the issue.

Why are Outlook Clients not receiving Emails for Longs Hours?

Outlook clients may fail to receive the emails or take long hours to fetch emails from the mailbox server when there are synchronization issues between the mailbox server and the client. This may also happen when there are issues with the mailbox server, the local cache (.ost), Office/Microsoft 365 profile, or the Outlook client itself.

Further, the following problems in Outlook client or system may also lead to sync issues between the server and the client:

• Large or oversized local cache
• Faulty or incompatible Outlook add-ins
• Mailbox reaching a maximum allocated size
• Conflicts with other apps, such as antivirus
• Email rules
• Inbox filters settings

Learn More, How to Fix Outlook and OWA Synchronization Issues?

Solutions to Fix Outlook not receiving Emails for Long Hours Issue

Follow these solutions to troubleshoot and resolve the Outlook client not receiving emails issue.

Check Office 365 Web Outlook

Open the Microsoft/Office 365 web version and log in to see if the email received is visible. If it isn’t, ask the sender to send it again. If you receive it instantly, your mailbox server is working fine. If you don’t, there could be a problem with the mailbox or you may have added email rules which are moving emails to a different folder or Junk folder.

Switch Off the Email Rules

You can change or switch off the Inbox and Sweep rules to fix the issue. The steps are as follows:

• Sign in to your Outlook 365 account via the web browser.
• Click on the gear icon in the top right corner. This opens a sidebar.
• Click View All Outlook Settings at the bottom of the sidebar.
• Click on Rules.
• If you find any Inbox or sweep rules, toggle the switch to the left to turn off the rule. You may also delete the rules permanently.

Restart Outlook and then check if your Outlook client is receiving new emails.

Manually Sync the Outlook Client

When auto-sync isn’t working, you can try to manually sync the mailbox in Outlook by using the Update Folder button under the Send/Receive tab.

After you click the button, the Outlook client will try to sync the mailbox and update all folders. Any new email received in your mailbox should immediately reflect in the Inbox folder unless you have added email rules or Office/Microsoft 365 spam filter policies to move it to the Junk Folder. You can check your folders to find the received email.

While this will let you retrieve the emails that are stuck or not synchronized for long hours, you may be required to do this often, which may become tedious. Thus, continue following the solutions below to fix the issue permanently.

Learn more, How to Fix – “Outlook 365 Stuck at Updating Inbox and Outbox“?

Disable Antivirus Temporarily

Conflict with the antivirus tools, especially when the tool isn’t Outlook-aware, is a common issue that can prevent the client from performing specific tasks or lead to delays in receiving emails. To check whether your antivirus program is causing the issue, disable it temporarily and restart Outlook.

Try sending emails to your Office 365 email account and then check your Inbox folder. If you receive the email within a minute, it indicates that the antivirus program is causing the issue. You may need to replace the antivirus with an Outlook-aware security tool or add Outlook processes as exceptions in the existing antivirus or security tool.

Run Outlook in Safe Mode

If any Outlook add-ins are causing the issue, then you can start Outlook in safe mode to check and remove the faulty add-ins. Follow the steps given below to run Outlook in safe mode.

• Close Outlook.
• Press Windows + R and type Outlook.exe /safe.
• Press the Enter key or click OK. This starts Outlook in safe mode.

If Outlook starts retrieving emails within a minute or so, you must find and remove the faulty or incompatible add-ins from Outlook.

Repair Outlook

Damaged or missing MS Office or Microsoft 365 Outlook program files may also cause issues in Outlook clients, causing delays in sending or receiving emails. You can try repairing the MS Office or Office 365 suite installed on your system to troubleshoot the “Outlook not receiving emails for long hours” issue.

The steps are as follows:

• Open Control Panel.
• Click Uninstall a program.

• Choose MS Office and then click Change.

• Choose the Repair option and click Continue. Follow the wizard to complete the MS Office repair.

This will restore any missing or damaged program files for MS Office and Outlook, thereby fixing the issue.

Disable Cached Exchange Mode (Offline Mode)

Office 365 email account is configured in Offline Mode or Cached Exchange Mode by default. However, you can disable the Cached Exchange Mode and enable the Online Mode. When in Online Mode, the Outlook client connects to the mailbox server, and any changes you make will be immediately updated on the mailbox server and reflected in the Outlook web version. Now if you receive any email, it will be shown in your Inbox folder directly.

However, you may experience issues while using Outlook in Online Mode on a poor network connection and cannot access emails when the system is not connected to the internet. If you want to keep Cached Exchange Mode for a better user experience, continue following the subsequent solutions.

Clear Outlook Cache

Clearing the RoamCache created by Outlook may also help you fix the problem of Outlook clients not receiving emails for long hours. The steps are as follows:

• Close Outlook client.
• Press Windows + R, type %localappdata%\Microsoft\Outlook\RoamCache, and press the Enter key or click OK.

• Select and delete all cache files from this folder.
• Start Outlook and test if you can now receive emails without having to wait for hours.

Reduce Outlook Data File and Mailbox Size

Problems with Outlook local cache or Outlook OST data file may occur when the OST is oversized or large. If the system does not have enough resources, Outlook may take longer to process tasks and information to or from a large OST file.

Learn More, Why OST File is Larger than the Mailbox?

To reduce the OST file size, you can try the following solutions:

• Compact the OST file.
• Archive old emails to a local PST file.
• Delete emails from the Junk or Trash folder.
• Empty the Deleted Items folder after inspection.
• Enable Auto-Archiving to prevent the issue in the future.

[Quick Fix] OST File Has Reached the Maximum Size?

Setup a New Outlook Profile

A corrupt Outlook profile may also lead to severe problems and Outlook performance issues causing the client to take hours to receive emails and update the mail folders. However, you can create a new profile and replace the corrupt profile to fix the problem permanently. The steps are as follows:

• Open Control Panel.
• Search and click on the Mail option.
• Click Show Profiles.

• Select the current profile and click Properties > Data Files.
• Select the data file and click Open File Location. Copy the OST file to a different location for backup.
• Go back to mail options, select the profile, and click Remove.
• Click ‘Yes’ to confirm the removal.

Note: Removing the profile will also remove the linked OST file from the default location. Thus, back up the OST file before removing the profile.

• Click Add.
• Enter the profile name and click OK.
• Enter your Office 365 account credentials and click Next to sign in.
• Follow the wizard to configure the account. This will create a new Outlook OST data file at the default location.
• In the Mail options, click Always use this profile and then choose the new profile name from the dropdown.

• Click OK.
• Open Outlook. The Outlook client will open your Office 365 email account under the new profile. It will download all mail items from the mailbox server. It may take a while to complete based on your mailbox size and network speed.

Once all mail folders and items are synced, check your folders for missing mail items. If you found any missing mail items, you can use an OST to PST converter tool, such as Stellar Converter for OST to extract missing mail items from the backup OST file that’s linked with the old Office 365 profile and save them to PST format. You can then import this PST to restore the missing mail items. The software also exports the mail items from the orphaned or inaccessible OST files directly to Office 365 or a live Exchange mailbox.

Conclusion

By following the solutions discussed in this detailed guide, you can troubleshoot and resolve common Outlook synchronization issues, such as Office 365 Outlook clients not receiving emails for long hours. Make sure to back up your current mail items before applying some of the solutions discussed in this guide, such as creating a new profile for Microsoft 365. It will help you restore missing mail items that were not synced to the mailbox server. You can use an OST to PST converter tool to extract the mail items, including deleted emails, from the backup OST file and save them in a PST file or export them directly to a live Exchange or Office 365 mailbox.

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About The Author

Eric Simson

Eric Simson is an Email Platform Consultant and is associated with Stellar Data Recovery from last 6 years. He writes about the latest technology tips and provides custom solutions related to MS Outlook, MS Exchange Server, Office 365, and many other Email Clients & Servers.