MBlaster Virus Blocks Outlook WAN Access????

Ever since the attacks of the MSBlaster Virus our WAN users have had to user
Outlook Web Access to access their email on our Exchange Server.

I am aware of many ISPs blocking Port 135 to contain the virus, and as a
result this has crippled remote Outlook users.

Questions

 1.. Is there a work around?
 2.. Has anyone heard how long this could/should/would last?

Thank you and best regards,

Ken