Can't Send/Receive E-mails - MS Storage Over but E-mail Storage Under

Question

Hi - I currently can't send/receive e-mails due to storage issues. When I go into Manage storage, I see two different buckets of storage that I have used - 6.0 GB of 5.0 GB for MS Storage and 9.0 GB of 15.0 GB for E-mail Storage. The vast majority of the MS Storage is due to Outlook (Attachments); however, I have deleted all Deleted E-mails, all Trash E-mails, and all E-mails > 5 MB and although this fixed the E-mail Storage, it hardly made a dent in the MS Storage. I have also waited a couple of days thinking the MS servers might need to catch up but still have the problem a couple of days after deleting all of those e-mails. Not sure what to do or who to contact - I understand I can just buy more storage but given that the management of the storage seems so unintuitive, I'm very reluctant to buy more storage and then have the same thing happen again to me in a few years because I can't understand the MS storage framework. Have had my hotmail account since early 1990s but now considering switching to a different e-mail provider just so I can send/receive e-mails. However, before I make such a drastic change, just want to make sure I'm not missing something obvious. Any help anyone could provide would be greatly appreciated. Thanks in advance. Rob