Sending, receiving, and organizing email in Outlook.com
Hi,
Sign in to Outlook.com and sort your Inbox by Size to find large emails and attachments. Delete Emails with larger attachments. If you need to keep emails with attachments, save the attachments to your computer or OneDrive first, then delete the emails.
In addition, Check the Sent Items folder, as large attachments sent by you also count toward your storage.
Last,Open Deleted Items and select Empty folder to permanently remove deleted messages.
I’m eager to hear back and work together to find a solution.