Creating wildcard tld doesn't work

[yonatan]

I used the following command to create a wildcard tld:

zmprov cd *.fax zimbraMailTransport smtp:faxserver.mydomain.com:25

It creates the domain fine, but when I try to send an email to:

test@1234.fax

It sends through the ISP's SMTP relay rather than to the host on my network, i.e. faxserver.mydomain.com.

What is the correct way to forward the .fax tld to my faxserver?

Thanks