Then right click or Ctrl+click on the highlighted messages, select Move and then select the local archive folder as the destination. To select all emails in a folder you can use the Edit menu and apply Select All or use CMD+A on your keyboard. Click the minus sign next to the conditions you do not want.
The dialog box that opens will have three criteria pre-filled, based on the message you selected: From, Sent To, and Subject.
This guide will explain how to create a local folder within Outlook for Mac and archive messages from your IMAP mailbox to local storage on your computer. This will allow you to free up space in your mailbox without permanently deleting your messages.
If your IMAP mailbox is full or starting to approach the disk space capacity you may need to archive messages by copying them to an offline location on your computer.