Restrict Mantis usage to specific domains

[vaidy]

Hi
We are a small group of users from different companies using the Mantis bugtracking tool & would like to restrict the usage of the tool to only the list of domains in our group.
I could check for the option

$g_limit_email_domain = 'mydomain.com';

But this option restricts to only one domain. Is there any other option to do this for a list of domains, eg. mydomain1.com, mydomain2.com etc.

I use Mantis 1.1.8 with mysql backend. The whole setup runs on a windows XP SP2 system.