How to archive IMAP messages in Mac Mail - LCN.com 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. This will allow you to free up space in your mailbox without permanently deleting your messages. This guide will explain how to create a local folder within Mac Mail and archive messages from your IMAP mailbox to local storage on your Mac. in Public bookmarkswith emailimap