The first thing that you might do is to access your mail account using the web interface. In the top left corner it will show the percentage of your mailbox in use. On the left side, find ‘Trash’ and click ‘Purge’. Next, have a look in ‘Sent’, select all, and delete. Purge the Trash folder again. By now, you should have some space in your mail box.

Not enough? You will have to delete some items from the Inbox. Remember to Purge the Trash Folder.

In order to avoid this problem, you may wish to re-configure MS Outlook. Click on File and on Account Settings (twice). In the account settings dialogue box, select the account and click on Change. In the bottom right corner click on More Settings. From the tabs across the top, select Advanced. In the Delivery section, remove the check mark next to the statement “Leave a copy of messages on the server”.

Click on OK, Next, Finished, Close.