Not getting Confirmation Mail

Let me add to that.

I have checked the troubleshooting steps at the URL below.
I had no problems with it, so I asked here.

https://support.box.com/hc/en-us/articles/360043696174-Troubleshooting-Issues-with-Email-Notifications

Hi there, 

Welcome to the Box Community, I'm happy to help!

I understand that your colleague is unable to login to Box and is not receiving confirmation emails.

Please have the affected user go to this page Support.box.com > click 'Support' > Contact Support > They will then see a line that says "If you are unable to sign in, click here." Please have the user fill out the form and we will reach out to help look into their login issue.

Regards,