Multiple SSL certificates

[Thomas]

My website is: http://www.digiprof.fr, if you click the "connexion"
button at the top right corner, you will be redirected to a
registration page which uses SSL.

I have a mail server administration application reachable at
http://www.digiprof.eu, you will get redirected to https and you
should see the certificate warning with www.digiprof.fr

I tried to setup Nginx in the same manner as this page:
http://wiki.apache.org/httpd/NameBasedSSLVHosts

But when I specify an IP address in listen, it doesn't work.