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Only a subset of your Exchange mailbox items are synchronized in Outlook

• Article
• 07/21/2022
• 6 minutes to read

• Applies to:

  Outlook for Microsoft 365, Outlook LTSC 2021, Outlook 2019, Outlook 2016, Outlook 2013

In this article

Symptoms

Consider the following scenario:

• You’re using Microsoft Outlook LTSC 2021, Outlook 2019, Outlook 2016, Outlook 2013 or Outlook for Microsoft 365.
• You’re connected to an Exchange Server mailbox.Notes
  • If you’re running Outlook LTSC 2021, Outlook 2019, Outlook 2016, or Outlook for Microsoft 365, this account might be your primary mailbox or another mailbox to which you have delegate access or another permission. This might be an additional, shared, or automapped mailbox, or public folders.For more information about this issue in Outlook 2019, Outlook 2016, or Outlook for Microsoft 365 related to shared mailboxes or public folders, see the following article in the Microsoft database:3140747 Only a subset of items is synchronized in shared mailboxes or public folders in Outlook 2016
  • If you’re running Outlook 2013, the account must be your primary account.
• Your Exchange email account is configured to use Cached Exchange Mode.

In this scenario, the email folders for these mailboxes may show item counts that are lower than expected. Additionally, older items may seem to be missing, and you might receive the following message and hyperlink at the bottom of the list of items:

There are more items in this folder on the server

Click here to view more on Microsoft Exchange

This message is shown in the following screenshot. Additionally, if you search for email items in your mailbox, the search results may display the following text at the bottom of the results:

Showing recent results…
More

If you click the More link, additional items that meet your search criteria are displayed in the search results. This occurs because Outlook retrieves the additional items from your mailbox on the server that’s running Exchange Server. Note This behavior can also occur in the RSS Feeds folder in your Exchange mailbox. Also, only a subset of items may be synchronized in groups in Outlook 2016 or Outlook for Microsoft 365.

Cause

This behavior occurs because the Cached Exchange mode Mail to keep offline setting is configured to a value other than All. For example, the following screenshot shows a profile that’s configured to use Cached Exchange Mode and the Mail to keep offline setting is set to a default value of 12 months. Note Outlook 2019, Outlook 2016, Outlook 2013 and Outlook for Microsoft 365 provide the options of 1, 3, 6, 12, or 24 months, or All. Outlook LTSC 2021, Outlook 2019, Outlook 2016, and Outlook for Microsoft 365 provide the additional options of 3 days, 1 week, 2 weeks, 3 years, and 5 years. Additionally, later versions of Outlook renamed the Mail to keep offline setting to Download email for the past. In the default configuration, depending on the size of your hard disk, Outlook synchronizes only 1, 3, or 12 months of email to your Offline Outlook Data (.ost) file from the Exchange server. If your Mail to keep offline setting is set to 12 months and you have email items in your Exchange mailbox that are older than 12 months, those items reside only in your mailbox on the server. Therefore, if you can’t connect to the Exchange server, you may be unable to retrieve items outside the range that’s specified by the Cached Exchange Mode synchronization setting until you reconnect with the server. Note This setting does not affect the number of items that are synchronized with folders of the following types:

• Calendar
• Contacts
• Tasks
• Journal
• Notes
• Outbox
• Shared or delegated (only for Outlook 2013)

Note Groups folders only synchronize a maximum of 1 year. Mail to keep offline settings that are lower than 1 year are honored.

More information

To reduce the effect of the Outlook offline data file (.ost), the default number of months that are configured for your profile varies by the size of your hard disk. The following table provides the different default values for different hard disk sizes.

Hard disk size	Default value for «Mail to keep offline»
Less than or equal to 32 GB	1 month
Greater than 32 GB, but less than 64 GB	3 months
Equal to or greater than 64 GB	12 months

If you have to change the number of selected months of email to synchronize with your cached mode «.ost» file, follow these steps:

1. Start Outlook.
2. On the File tab, click Account Settings, and then click Account Settings.
3. On the E-mail tab, double-click your Microsoft Exchange account.
4. In the Change Account dialog box, drag the Mail to keep offline slider to the desired number of months or to All to synchronize all email messages.
5. Click Next.
6. Click OK when you’re prompted to restart Outlook to complete the configuration change.
7. Click Finish.
8. Restart Outlook.

Working Offline

If you don’t have connectivity with the Exchange server, the following message is displayed in a folder if there are older items on the server that were not synchronized with your .ost file:

There are more items in this folder on the server

Connect to the server to view them

This message is shown in the following screenshot. Under similar conditions, if you search for items in your mailbox and you don’t have connectivity with the Exchange server, the following message is displayed below the search results: Server unavailable. <x> months of results shown. In this message, <x> represents the value that’s configured for the cached mode Mail to keep offline setting. An example of this message is shown in the following screenshot.

Feature Administration through Group Policy

The cached mode Mail to keep offline setting is maintained in the Outlook profile settings in the Windows registry. If you want to administer this setting by using Group Policy, you can use the Group Policy templates. These are available from the following Microsoft websites, depending on your version of Office: Office 2016, Office 2019, Office LTSC 2021, or Outlook for Microsoft 365: https://www.microsoft.com/en-us/download/details.aspx?id=49030 Office 2013: https://www.microsoft.com/download/details.aspx?id=35554 The Group Policy template files for Outlook 2016, Outlook 2019, Outlook LTSC 2021, and Outlook for Microsoft 365 are Outlook16.admx and Outllk16.adml. The files for Outlook 2013 are Outlk15.admx and Outlk15.adml. If you use Group Policy to manage this setting, the following registry data is used by Outlook: Key: HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\<x.0>\Outlook\Cached Mode DWORD: SyncWindowSetting Value: integer value (Decimal) specifying the number of months (use only the following values)
0 = All (whole mailbox) 1 = 1 month of email items 3 = 3 months of email items 6 = 6 months of email items 12 = 12 months of email items 24 = 24 months of email items 36 = 3 years of email items 60 = 5 years of email items Notes:

• The <x.0> placeholder represents your version of Office (16.0 = Office 2016, Office 2019 or Outlook for Microsoft 365, Office 2019, Outlook LTSC 2021, or Outlook for Microsoft 365, 15.0 = Office 2013).
• The Outlook 2016, Outlook 2019, Outlook LTSC 2021, or Outlook for Microsoft 365 user interface (UI) lets you set the Mail to keep offline setting to the additional values of three days, 1 week, 2 weeks, 3 years, and 5 years. The May 3, 2016, update for Outlook 2016 allows you to set these additional values by using the SyncWindowSettingDays registry data. For more information about how to configure Outlook 2016 with these additional values, see the following article in the Microsoft Knowledge Base:3115009 Update allows administrators to set additional default mail and calendar synchronization windows for new Exchange accounts in Outlook 2016.
• Administrators who change the existing GPO values should be aware of the potential to impact network traffic when raising the value of the SyncWindowSetting. When GPO changes SyncWindowSetting to any higher value, Outlook will do a full OST resynchronization when the new value applies. For a single client, this is not problematic. Applying a higher value to hundreds or more clients at the same time could adversely affect available network bandwidth. Decreasing the value will have no such impact because Outlook will do a local-only deletion of excess data that’s cached in the OST files of all clients to receive the lower SyncWindowSetting value.
• Since Outlook only synchronizes a maximum of one year for groups, you are unable to search for older messages. To work around this Outlook limitation, use Outlook on the Web to view and search for older messages in groups.

You might think that Outlook will display all of your mail (after all, why wouldn’t it) but by default, the Outlook client only keeps the last year of email on your computer. All of your mail still exists on the Microsoft Exchange server but it’s not visible on Outlook. Here’s why Microsoft sets this default and how to change it if you want. Note: The following information covers all versions of Outlook from 2013-2019, including Outlook 365. It also only applies if you’re connecting to a Microsoft Exchange server, and that includes if you connect to Hotmail or Outlook.com. If you connect to another service, like Gmail or a personal mail server, you can configure these options, but Outlook will ignore them.

Why Doesn’t Outlook Show All of my Mail?

When you install Microsoft Office, it checks your disk size to make sure you have enough space to install all of the applications. It also uses that check to set a parameter in Outlook that determines how much mail will be downloaded to your local machine, based on the following disk sizes:

• Less than or equal to 32 GB: Outlook retains one month of email on your system.
• Between 32 and 64 GB (not inclusive): Outlook retains three months of email.
• Equal to or greater than 64 GB: Outlook retains 12 months of email.

Microsoft does this because mail takes up space on your hard disk, and if you’ve only got a small hard disk, you probably don’t want much of it taken up with a few large files someone emailed you two years ago. Outlook still downloads all of your calendar appointments, contacts, tasks, and everything else. This limit only affects your mail (and your RSS feeds). If your mail account uses a Microsoft Exchange server (like Hotmail, Microsoft Live, O365, or a lot of corporate mail systems), then this parameter will determine how much mail is downloaded to your computer. If you’re using a different mail provider, like Google or Yahoo, Outlook ignores this parameter and downloads all of your mail.

Where is My Mail and How Do I Access It?

The good news is that your mail hasn’t gone anywhere; it’s still on your email server. (If you’re not sure what an email server is, the short answer is that it’s a powerful computer with a large hard disk on which your email provider stores all of your mail. We’ve written a longer answer, which is worth reading.) You can access your mail at any time (as long as you have internet access) either through Outlook or, depending on your version of Outlook, through a web interface. To see your mail in Outlook, scroll down to the bottom of the folder. If there are more emails on the email server, you’ll see a message letting you know. Hit “Click here to view more on Microsoft Exchange,” and Outlook will download the rest your emails to your computer. Make sure you’ve got adequate disk space to download them all! RELATED: 7 Ways To Free Up Hard Disk Space On Windows If you’ve got Office 365, you can also access your emails through the Outlook web app. Because the web app is essentially just a window into the Exchange Server, it will show you all of your emails. If you’re using Outlook at work, your IT support people should be able to help you access the Outlook web app. If you’re at home, head over to Office.com and sign in there. You can access Outlook—and any other web apps to which you have access—once you’re logged in.

Can I Change the Default Value?

Yes, you can. In Outlook, head to File > Account Settings and then select “Account Settings” from the drop-down menu. In the Account Settings window, select the account for which you want to change the default (you’ve probably only got one account) and then click the “Change” button. In the Change Account window that opens, you’ll see that the “Use Cached Exchange Mode” is enabled. You must leave this enabled, otherwise, no mail will be downloaded to your computer. Move the “Mail to keep offline” slider to the period you want. The options are:

• Three days
• One week
• Three weeks
• One month
• Three months
• Six months
• One year
• Two years
• Five years
• All

Note: The three days, one week, and two weeks options aren’t available in Office 2013, but they are in later versions. Choose “All” if you want Outlook to download all of your mail to your computer, or choose whatever value works for you. (If you can’t change the slider then your administrator may have set this value deliberately and stopped you from changing it.) Once you’ve made your selection click “Next” and Outlook warns you that it needs to restart. Click “OK,” close the Account Settings window, and then restart Outlook. Depending on the amount of mail it has to download, Outlook might take a little while to update each folder. You’ll see a message at the bottom of Outlook as it downloads mail into each folder. And that’s it; you’re done. Outlook will now download all of your mail (or however much you selected) from now on. READ NEXT

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Outlook is the primary emailing interface for Microsoft Exchange Server users. It is synced with the server to fetch and send emails quickly and handily. It doesn’t matter whether your email client is Outlook.com, Hotmail, or even a third party like Gmail, you can easily set up your account and start sending all those work emails. Since they’re your emails, you would, of course, want the ability to open them at any time. You can depend on Outlook displaying any email you need no matter how many months have passed since you wrote it. Or can you? As it turns out, things aren’t that simple. Outlook doesn’t display everything by default: most of your emails remain on Microsoft Exchange Server, while only a portion are made available for you in Outlook. If you’re using Outlook 2019, 2016, 2013, or Outlook for Office 365, you can’t get instant access to your older emails without changing an inbox setting. Although your email is kept on the server forever if you so wish, you might expect the convenience of also having a local copy. However, the way Outlook is set up, it downloads up to 12 months of your emails to your local disk. If you need to read emails older than this date, you will have to take the appropriate action to force Outlook to download them from the server.

Why Does Outlook Have an Email Download Limit?

You might wonder why the situation is like this. It is because Microsoft Office makes some intelligent settings when it’s installed on your system. It checks all your hardware and makes the necessary adjustments to allow the program to run optimally on the system. With respect to Outlook and enterprise emails, the checks it performs on your hardware are used to set download parameters. Plainly, it is trying to help, but the program can become meddlesome. After checking your hard disk to verify how much space is left, it automatically adjusts the time limit that determines how many of your emails are retained locally. The more disk space is available, the more months of emails are downloaded. The calculation is made according to the following formula:

• If free disk space is up to 64 gigabytes, up to 12 months of emails are automatically downloaded to your computer.
• If free disk space lies somewhere between 32 gigabytes and 64 gigabytes (not including either number), three months of emails are automatically downloaded to your computer.
• If the amount of free space on the disk is less than 32 gigabytes, only a month’s worth of emails are retained on your computer’s local storage.

You might wonder what the fuss is about and why the setting couldn’t just be set to “download all emails” or something similar. Actually, contrary to popular belief, emails can take up a lot of storage. Those who lead busy email-laden lives often find that a huge amount of space has been taken up by both sent and received emails. If you don’t monitor your disk usage, you might wake up to find all your space has been swallowed up by your business correspondence. Microsoft knows this as well. That is why Office is designed to automatically adjust storage parameters, such as the default local email storage limit for Outlook. Usually, this is okay; chances are you don’t have much need for emails of bygone years. Moreover, irrespective of the setting, you still get local access to your tasks, calendar appointments, and contacts. Keep in mind that the efficacy of this setting is dependent on the kind of email client you use. If you utilize one of Microsoft’s homegrown email service providers like Hotmail, Outlook or 0365, the setting does influence how many emails are available locally. The same principle applies to the majority of popular business email services around. However, if you happen to use a public provider like Gmail, Yandex or Yahoo, you won’t have this worry since the setting won’t have any effect. All your emails on Microsoft Exchange Server will have a local copy stored on your computer’s internal storage.

How to Make Outlook Download All Emails From the Server

The server here naturally refers to Microsoft Exchange Server. While some businesses purchase a license to host an Exchange Server in the premises, others turn to a third-party Exchange-as-a-Service server provider. The popularity of Exchange Online, a cloud version of the service hosted by Microsoft itself, is on the increase as well. Irrespective of the mode of Exchange used, its main function remains the same: a message transfer agent that sends emails between computers. The messages are read on both ends by means of an email client, in this case, Outlook. In essence, by using Exchange, all the emails you’ve ever sent and received are stored on the Exchange Server in perpetuity. Of course, the eternal retention of your emails is subject to things like cloud storage limits for individual accounts and continuous use of the account. The point remains that under normal circumstances, you can still see your emails, including the really old ones, even if they aren’t stored on your computer. So, what can you do to download all the emails from the server to Outlook? If you wish to view all your emails in Outlook, there are two ways.

Method 1: Use the “More” link in Outlook

Outlook for Office offers an easy way to extend the number of emails displayed in a folder. Assuming that you’ve maintained the account for a long time or have a long email history, the app will typically display only the most recent emails. But you can force Outlook to download all IMAP emails — or display them, at least. When you are in a folder such as Inbox or Sent in Outlook and scroll down, you soon reach the end of the displayed emails. Right there, you will see a message informing you that you can click the link to view more messages: There are more items in this folder on the server Click Here to view more emails on Microsoft Exchange Once you click the “Click Here to view more emails on Microsoft Exchange” link, Outlook will download the rest of the emails for that folder to your computer. This only works if you have an internet connection. Plus, only the emails for a particular folder are downloaded. Thus, if you are in the Sent folder, you get only all the emails you’ve ever sent. This principle holds true if you conduct a mailbox search. When you type your search query and results are displayed, if there are plenty of emails matching the search term, you may see the following at the bottom of the results page: Showing recent results… More Clicking the More link downloads the rest of the emails matching your search query. If you wish to see all your emails in a certain folder at a glance, you can log into your account via the web app for Outlook. That takes you to the Microsoft Exchange Server interface for your account, and you can see everything stored there.

Method 2: Change the “Mail to Keep Offline” Setting in Outlook

This is the setting that determines how many months’ worth of emails Outlook keeps on your computer. Remember that this only works when using a Microsoft email client or a recognized business email service provider. You can extend the number of kept mails or reduce it, even. You can also tell Outlook to save each and every one of your emails locally.

According to Microsoft:

Outlook 2019, Outlook 2016, Outlook 2013 and Outlook for Office 365 provide the options of 1, 3, 6, 12, or 24 months, or All. Outlook 2019, Outlook 2016, and Outlook for Office 365 provide the additional options of 3 days, 1 week, and 2 weeks.

Without further ado, here is what you need to do:

• Launch the Outlook application.
• Head to the File tab.
• Select the Account Settings drop-down option.
• When the option is expanded, select Account Settings.
• In the Account Settings window, select the Email tab.
• If you have multiple accounts in Outlook, they will be displayed here. Select the one whose settings you wish to adjust and then click the Change button.
• The Change Account dialog is displayed. Make sure that the Use Cached Exchange Mode checkbox is ticked.
• Move the “Mail to keep offline” slider to the desired number of years, months, days, or weeks. (If the slider is grayed out, your administrator may have blocked you from changing the setting.)
• Click the Next button.
• A pop-up appears asking you to confirm the configuration change. Click OK.
• Click Finish and restart Outlook.

You should soon see a message informing you that “Your folders are up to date” at the bottom of Outlook. This only appears after Outlook has finished downloading all your messages from Microsoft Exchange Server. Only choose the All option if there is enough storage. Your settings should match the amount of space on your disk. If you choose the option to download all emails to a disk with limited space, problems are inevitable. We recommend that you delete all unwanted items from your storage first to free up more space. Naturally, you may find it hard to decide what to remove from your storage, so we are here to help you. Did you know that apart from the obvious files on your system, there are also junk files that serve no purpose apart from inflating your storage use? Of course, you’d want to get rid of them, but finding where they are might be an issue. RECOMMENDED

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