<VirtualHost  *:443>
 ServerAdmin    admin@blah.fr
 ServerName     admin.blah.fr
 DocumentRoot   /var/www/admin
 CustomLog      /var/log/apache2/access_log.admin.blah.fr.log combined
 ErrorLog       /var/log/apache2/error_log.admin.blah.fr.log
 SSLEngine On
 SSLCertificateFile /etc/postfix/sasl/smtpd.cert
 SSLCertificateKeyFile /etc/postfix/sasl/smtpd.key

</VirtualHost>



<VirtualHost  *:80>
 ServerAdmin    admin@blah.fr
 ServerName     admin.blah.fr
 ServerAlias    blah.fr
 DocumentRoot   /var/www/dummy
 
 CustomLog      /var/log/apache2/access_log.admin.blah.fr.log combined
 ErrorLog       /var/log/apache2/error_log.admin.blah.fr.log
 #SSL
  RewriteEngine On
  RewriteRule ^/$ https://admin.blah.fr/ [L]
   
</VirtualHost>