It is important to archive emails when mailboxes start reaching their limit.

  1. In Outlook, Click File.

  2. Then while selected on the "Info" tab, click on Tools > Clean up old items.

  3. Ensure that you click your email, as shown below so that when the archive runs it will include everything in your mailbox. Then set an archive date to a couple of months before. Be sure to check "Include items with "Do not AutoArchive" checked". Then browse to a suitable location on the local drive and save with a identifiable name e.g. archive_mailboxname_2018.