Sending, receiving, and organizing email in Outlook on the web for business
Hi Kanto,
Since a self-sent message was delivered, your mailbox is still active, but messages from external senders may be blocked, rejected, redirected, or not synchronized with the current Outlook client.
For the best assistance in this case, please ask your son whether he received a bounce-back or non-delivery report, and share with me the full wording of the error message if one exists. This will help determine whether this is an Outlook synchronization issue or a mailbox delivery issue.
Thank you for your cooperation and understanding. Hope to hear from you soon.