[Fixed] Outlook Performance and synchronization Problems with the Folder in the Secondary Mailbox

Outlook users may encounter random performance and synchronization issues while accessing the mail folders and items from a secondary MS Exchange Server mailbox added to their Outlook profile. This is due to the fact that Outlook 2010 and later versions create an OST file and locally cache all your mail folders and shared folders.

When there are a large number of folders or items synchronized from the secondary mailbox and if the option to download a shared folder is enabled, it can significantly inflate the local cache (.OST) file size, which can lead to Outlook performance and synchronization issues.

Also, the performance problem with the secondary mailbox is more likely to occur in Outlook 2007 if the following registry key (with DWORD: CacheOthersMail and Value: 1) is configured on your system for the Outlook client.

HKEY_CURRENT_USER\Software\Microsoft\Office\12.0\Outlook\Cached Mod

Or, 

HKEY_CURRENT_USER\Software\Policies\\Microsoft\Office\12.0\Outlook\Cached Modee        

In this article, you will learn about various performance and synchronization problems that may occur when working with or accessing a secondary mailbox in Outlook and the solutions to resolve them

Common Performance and Synchronization Issues with Secondary Mailbox in Outlook

While accessing folders from the secondary mailbox in Outlook, users may encounter one or more of the following performance and synchronization issues.

• Missing mail items or outdated secondary mailbox (new mail items may not appear).
• Outlook loads slowly.
• Outlook stops responding.
• Changes are not reflected in the secondary mailbox. For instance, deleted items are still appearing in the secondary mailbox in Outlook.
• The sync Issues folder contains multiple synchronization issues logs, such as:

07:20:38 Synchronizer Version 16.

07:20:38 Synchronizing Mailbox 'Ravi Singh'

07:20:38 Synchronizing Hierarchy

07:20:38 Synchronizing server changes in folder “Folder Name’

07:20:38 Downloading from server ‘[email protected]’

07:20:38 Syncmonitor triggered for ;Folder Name’ (0x80004005)

07:20:38 Error synchronizing folder

07:20:38?[80004005-501-4B9-560]

07:20:38?The client operation failed.

07:20:38 Microsoft Exchange Information Store

07:20:38???? For more information on this failure, click the

URL below:

07:20:38????????? https://www.microsoft.com/support/prodredirect/outlook2000_us.asp?err=80004005-501-4b9-130

07:20:38 Done

07:20:38 Microsoft Exchange offline address book

07:20:38 Download successful        

Solutions to Fix Performance and Synchronization Issues with Outlook Secondary Mailbox

Apply the following solutions in the given order to troubleshoot and fix the performance and synchronization problems with the secondary Exchange mailbox in Microsoft Outlook.

Reduce the Number of Folders

Reducing the number of folders in the shared folder can help fix the performance and synchronization problems in Outlook. If it’s not possible, you may try to disable the shared folder caching for specific or all shared folders. ?

Disable Shared Folder Caching

You can disable Shared Folder caching to fix the synchronization problem in MS Outlook. The steps are as follows:

• In Outlook 2010 and later versions, navigate to File > Info > Account Settings > Account Settings.
• In Outlook 2007, go to Tools > Accounts Settings.
• Select your Outlook profile and click the Change button.
• Click on the More settings button.
• Click the Advanced tab and uncheck the Download shared folder option.

• Make sure “Use cached Exchange” is checked.
• Click Apply > OK and restart Outlook for the changes to take effect.

After the restart, you may experience performance improvement and synchronization issues should be fixed by now. If not, try disabling Cached Exchange Mode.

In Outlook 2007, you also need to check and delete the CacheOthersMail registry located at one of the following locations

HKEY_CURRENT_USER\Software\Microsoft\Office\12.0\Outlook\Cached Mod

Or,

HKEY_CURRENT_USER\Software\Policies \Microsoft\Office\12.0\Outlook\Cached Mode        

Notes:

• Deleting registry keys can cause issues. Thus, ensure you follow the right path and delete only the registry key mentioned above.
• ?It is recommended that you keep caching or Cached Exchange Mode enabled for Exchange and Office 365 accounts on a slow network to avoid issues due to poor network connections. ?

Modify Outlook Profile

If you can’t reduce the folders or disable the caching for all shared folders, you can modify your Outlook profile and add the secondary mailbox as a second Exchange account. This will create a separate OST file for the secondary mailbox and help fix the performance and synchronization issues in Outlook.

The steps are as follows:

Step 1: Remove Secondary Mailbox from Outlook Profile

Follow these steps to remove the secondary mailbox from your Outlook profile.?

1. In Outlook 2010 and later versions, go to File > Info > Account Settings > Account Settings.
2. Click the E-mail tab and select your Microsoft Exchange Server account.
3. Click More Settings.
4. Click the Advanced tab.
5. Select the secondary mailbox and then click Remove.
6. Click Yes to confirm the mailbox removal.
7. Click OK > Next > Finish and then click Close.
8. Exit the Outlook.

This will remove the secondary Exchange mailbox from your Outlook profile

Step 2: Setup New Profile for the Secondary Mailbox

Follow these steps to create a new profile and set up a secondary mailbox.

• Open Control Panel. Search and click on the Mail option.
• Click Email Accounts and then click New.

• Select E-mail Account, and then enter the email address and password for the secondary mailbox account (if you know). Click Next > Finish to complete the setup.
• If you do not know the password but your account has full permission to access the secondary mailbox, enter the email and click Next > Finish.

• In the Auto Account Setup section of the Add New Account dialog box, enter the account information for the secondary mailbox and then click Next.
• Make sure to enable the Cached Exchange Mode for the secondary mailbox to allow local caching in the .ost file.
• Once done, restart Outlook.

This should fix the performance and synchronization issues when you work with folders in the secondary mailbox in Outlook.??

Conclusion

Performance and synchronization issues in Outlook occur when the local cache (.ost) or a number of folders in the secondary Exchange mailbox grows larger and exceeds the recommended limits. This generally happens when synchronization is enabled for shared folders or the secondary mailbox is added to your existing Outlook profile instead of a new (separate) one. If not resolved, such issues can lead to an inaccessible OST file, resulting in the loss of mail items.

By reducing the number of folders from synchronization and disabling cache for certain or all shared folders, you can fix the problem. You may also create a separate profile and set up the secondary mailbox under this new profile to avoid performance and synchronization issues in Outlook. We have?covered the solutions with detailed instructions in this guide to fix the issues. However, if the issues are not resolved or the OST becomes inaccessible/orphaned, you can use an OST to PST converter tool, such as Stellar Converter for OST to extract the mail items from such OST files and save them to an Outlook importable PST format. The software can also help you export mail items from inaccessible, orphaned, or encrypted OST files to live Exchange and Office 365 mailboxes.?