If you're the owner of a group in Outlook on the web, you can apply labels based on policies that control how long a group conversation will be retained. The labels you choose are created by the administrator for your organization.
Note: You'll only be able to label your conversations if your administrator has turned on this feature for your organization or school.
Here's an example of week, month, and year retention labels:
Apply a label to a conversation
Right-click the conversation you want to label.
Select Assign policy > Labels.
Choose the label you want to apply to your conversation.
If you're an administrator, see the following topics: