You might think Outlook will display all of your emails (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 messages still exist on the Microsoft Exchange server, but they are 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 to 2019, including Outlook 365. It also only applies if you are connecting to a Microsoft Exchange server, and this includes if you are connecting to Hotmail or Outlook.com. If you connect to another service, such as Gmail or a personal mail server, you can configure these options, but Outlook will ignore them.
Why doesn't Outlook display all of my messages?
When you install Microsoft Office, it checks your disk size to make sure you have enough space to install all the apps. It also uses this check to define a setting in Outlook that determines the amount of mail to download to your local computer, based on the following disk sizes:
Less than or equal to 32 GB: Outlook keeps one month of email on your system.
Between 32 and 64 GB (not included): Outlook keeps three months of email.
Equal to or greater than 64 GB: Outlook keeps 12 months of email.
Microsoft does this because mail takes up space on your hard drive, and if you only have a small hard drive, you probably don't want a lot of it to be occupied by a few large files that someone emailed you two years ago. Outlook always downloads all of your calendar appointments, contacts, tasks, and everything in between. This limit only affects your mail (and your RSS feeds).
If your email account uses a Microsoft Exchange server (such as Hotmail, Microsoft Live, O365, or many corporate email systems), this setting will determine the amount of mail downloaded to your computer. If you use another email provider, such as Google or Yahoo, Outlook ignores this setting and downloads all of your messages.
Where is my mail and how do I access it?
The good news is that your mail has gone nowhere; it is still on your mail server. (If you are not sure what a mail server is, the short answer is that it is a powerful computer with a large hard drive on which your email provider stores all of your mail. We wrote a longer answer, which is worth reading.) You can access your email at any time (as long as you have internet access) via Outlook or, depending on your version of Outlook, via a web interface.
To view your mail in Outlook, scroll to the bottom of the folder. If there are more emails on the mail server, you will see a message informing you.
Click "Click here to learn more about Microsoft Exchange" and Outlook will download the rest of your emails to your computer. Make sure you have enough disk space to download them all!
If you have Office 365, you can also access your emails through the Outlook web app. Since the web application is basically just one window on Exchange Server, it will show you all of your emails. If you are using Outlook at work, your IT support staff should be able to help you access the Outlook web application. If you're at home, go to Office.com and sign in. You can access Outlook, as well as any other web apps you have access to, once connected.
Can I change the default value?
Yes you can. In Outlook, go to File> Account Settings, 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 probably only have one account), then click the "Change" button.
In the Change Account window that opens, you will see that "Use Cached Exchange Mode" is enabled. You must leave this option enabled, otherwise no mail will be downloaded to your computer. Move the "Mail to stay offline" cursor to the desired period.
The options are:
Note: The three days, one week, and two weeks options are not available in Office 2013, but they are available in later versions.
Choose "All" if you want Outlook to download all of your messages to your computer, or choose the value that suits you. (If you cannot change the slider, your administrator may have deliberately set this value and prevented you from changing it.)
Once you've made your selection, click "Next" and Outlook will warn you that it should restart.
Click "OK", close the Account Settings window, then restart Outlook. Depending on the amount of mail to download, Outlook may take a while to update each folder. You will see a message at the bottom of Outlook while it downloads mail to each folder.
And that's it; you have finished. Outlook now downloads all of your mail (or whatever you have selected) from now.