Hi there,
In order to receive an email, it must always come from somewhere. There will always be a sender email address, as it's not possible to send an email without disclosing such info.
You are using the Outlook.com webmail, correct? If so, you can open up the email in question, and it should show the sender chosen name (which appears to be 0 as you mentioned?), as well as their email address. You can also click their sender name once you open the email, and it should also show their email address there as well.
When looking through your inbox, it will generally show the chosen sender name rather then their email address. So opening up the email message will show their email address.
Hope this helps
Kind Regards,
Dave
Microsoft Community Member