Hello, thank you for reaching out to Microsoft Q&A.
May I please know the exact error message the sender receives when they try to send an email to your account?
Send a test email from another one of your accounts to the affected email address. Check whether you receive any bounce-back (non-delivery) error messages or if the email gets stuck in the Outbox. If you receive an error, please share the complete error message here.
If the email is sent successfully, then please check your email forwarding rules and blocked senders list, and verify whether the messages have been routed to another folder, such as Junk or Spam.
To check the forwarding rules, open this link on any web browser.
Email forwarding rules: https://outlook.live.com/mail/0/options/mail/forwarding
(Click Do not forward if your emails are being forwarded to another address)
Additionally, check that you have enough mailbox storage space available to send and receive emails.
(Go to Settings > Mail > Account > Storage)