What is a retention policy?
Retention policies are created by your organization. They manage how long data is stored in the Microsoft apps you use. In Teams, these policies decide how long messages show in a chat or channel and even how long a file is stored in Teams, OneDrive, and SharePoint.
If your organization sets an expiration date for messages, a system message will replace the ones deleted by your org’s retention policy—including messages that you've pinned or saved. If the original post in a channel conversation expires, only the post will be deleted. All replies that are still within the retention period will remain.
Note: Messages deleted by your organization’s retention policy can’t be recovered.
Files that are shared via a chat or channel message may have their own retention policy with a separate expiration date from the message. In those cases, the message and file preview may still show in Teams, but if you attempt to open the file, you’ll receive an error message that says, “File not found”.
If you’d like to learn how organizations create their retention policies, you can go to this technical document for IT admins: Create and configure retention policies
How do I delete messages before the expiration date?
If you want to delete a message before the retention policy does, simply hover over the message and select More options > Delete.
Note: You can only delete the messages you’ve sent so that you and others in Teams no longer see these messages. However, your organization might have configured a retention policy to retain a copy for compliance reasons.