Software

Please, I've got MDaemon 6.8.5 and the Antivirus for MDaemon 7 installed on my Windows 2000 Advanced Server mail server. For the past couple of months, I've realised that mails sent from my site to other sites only get into the bulk and not the inbox folder. I also have frequent attacks by the Netsky worm. Please, how can I:
1.) Solve the problem of mails sent from my site going to the bulk folder of other sites; and
2.) Blocking the Netsky worm from mails directed to my server?
Thanks.