If your IMAP mailbox is approaching the disk quota limit for your account or is full, you can either purchase more space or you can archive old emails by moving them to an offline location on your computer. This will free up space without having to delete messages. You can't create an additional folder in your IMAP account as this will just get sync'd with the server and you will not gain any space.
This guide demonstrates how to create an archive location in Outlook 2016. It can also apply to Outlook 2007/2010/2013 also but the tabs/menus and locations may be slightly different.
1. You need to create a new data file. You can either do this from Outlook or via the Control Panel --> Mail
5. Open Outlook and navigate to your new data file. Then right click and add 'New Folder'. You can mimick your current mailbox setup or have just one folder.
You can now drag and drop the message you want to archive from you IMAP mailbox to your new local archive data file. You can also use the auto-archive feature of Outlook to do this on a regular basis.
Once you have done this you can see you folder size by either loggin into your webmail at https://webmail.nuttyabouthosting.co.uk or view the email account in your hosting portal. This is found under POP/IMAP Email --> Accounts --> Your email account --> Account Information
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