The following tips may be beneficial in helping you to locate your missing emails.
Outlook Desktop by default will load 12 months of emails. Email Retention will move emails that are older than 24 months to your archive (see Email Retention below). If you are not seeing emails that you received between 1-2 years ago in your mailbox, adjust your cached mode settings to load more. Information Services does not recommend disabling cached mode, as it can cause other issues. See Turn on Cached Exchange Mode to learn how to adjust the amount Outlook Desktop loads.
The DePaul email system does not currently have any processes in place that delete emails from your primary Inbox or subfolders, only the Deleted Items folder will purge automatically. However, there is a policy in place that might have moved older items into your archive mailbox. Please review the following article to ensure the missing emails were not affected by our current policy settings.
BlueM@il: Email Automatic Archiving and Deletion Policy
If multiple searches are returning mixed results, it may be that your search indexing is broken. If your are getting mixed results, or can locate the email by browsing to it but not with search, try repairing your search index.
There is a limit to the number of emails returned with a single search. It is important to be specific when using the search function. Microsoft has provided documentation with helpful tips as to how to form your searches to efficiently find messages.
With the ease of drag and drop abilities as well as ability to delegate others access to email, it is possible for emails to have been accidentally moved or deleted. If your search is functioning properly, it should return results even if the emails were moved to another folder or mailbox within your view. Some other locations to look are detailed below.
Outlook has a keyboard shortcut where if you select an email and hit the backspace key, it will move that item to the Archive folder. If you do not realize that Outlook has the input focus at the moment and start typing backspace, you would have no idea it was moving things because it does not give you a prompt before moving them.
Deleted Items are not retained indefinitely. If the items were deleted within the retention period, you should be able to locate them here.
If you empty your Deleted Items regularly, you may need to go into Recover Deleted Items by right clicking on the Deleted Items folder.
If the mailbox in question is accessed by another, also check their Deleted Items and Recover Deleted Items.
It is entirely possible that another with access to the emails accidentally moved them to one of their own subfolders or another mailbox they have access to. Have them perform a search within their own email client.
If it is within 90 days of the email disappearing, Information Services may be able to assist in locating them. If you have not been successful in locating them after running through the steps above, open an Incident to get further assistance from Information Services.