Sending, receiving, and organizing email in Outlook.com
Hello Tinn Plangpongpan,
You’ve already checked Junk and the sender settings, so I wouldn’t repeat those steps.
Could you send a fresh test email to your Outlook.com address from a different account? If that also fails to arrive, we should look at the mailbox more broadly. If it arrives and only Discord’s messages are missing, please check for any unfamiliar rules or forwarding left after the compromise, then ask Discord Support whether its message was sent successfully or bounced.