Checking Mailman Configuration

I have mailman running on my server with two different domains. It has always worked in the past but it doesn't deliver the mail now. We just moved from Listserv listing to mailman and are having problems with emails not being delivered to work acocunt and hotmail accounts. We just want someone to check our configuration on server, dns, mx and anything else which will help us resolve this issue. Your help in this matter will be really appreciated. Thanks, WIth Regards,