Can't receive emails at my original xxx@zoho.com address, only at xxx@zohomail.com

Can't receive emails at my original xxx@zoho.com address, only at xxx@zohomail.com

Hello, I have since many years an email at a xxx@zoho.com address. This has been changed by the system without my doing to a xxx@zohomail.com address. The xxx@zohomail.com address works, but when I send emails to the old xxx@zoho.com address they bounce with an error message: "<xxx@zoho.com> User unknown"

I still can login into my account with the old address, so it's still registered, I just can't receive emails at it.

How do I reactivate the email reception for the original xxx@zoho.com address?

Please help, I need this address urgently, as I have several website accounts registered with it, and I can only maintain them (change passwords/email etc) when the email is working.