smtp clogged up with spam

[derwent]

Since the start of the year we have been receiving a hell of a lot of rubbish sent using online forms on our website.

The forms are set up with cdonts, I have just looked through the C:\Inetpub\mailroot\Queue and it is full of emails such as
-----------------------------------
This is an automatically generated Delivery Status Notification.

Delivery to the following recipients failed.

lgzu@sinamail.com
lgzv@sinamail.com
lgzw@sinamail.com
lgzx@sinamail.com
lgzy@sinamail.com
lgzz@sinamail.com

------------------------

I couldn`t even open the badmail folder it must be huge! THis is preventing real emails from the website coming through (we usually get about 20 per day real ones).

Is there anything I can do to stop all of this rubbish??

Thanks folks

 

[WhoKilledKenny]

Are you using the SMTP service of IIS to accept only the mail from the web-site or is it also being used as an SMTP gateway for your internal email system? If it is being used as a gateway and you are using Exchange, you can set up filtering to block spam. You could also look as SPAM filtering products such as Symantec Brightmail, which will work should the IIS server be stand alone SMTP or a Gateway.