Sending, receiving, and organizing email in Outlook.com
Hello Amy Payne,
Since this started right after the account was hacked, I would first check whether anything was changed in your mailbox settings.
Please sign in to Outlook.com in a browser and check Settings > Mail > Rules and Forwarding. Remove anything you don't recognize or didn't create yourself.
After that, send a test email to the account from another email address. If it still doesn't arrive, does the sender receive a bounce-back or error message? If so, please share the exact error message, without including any personal information.
That should help narrow down whether emails are being redirected or whether there is a separate delivery issue.