Spam blocker confusing my messages

I run a website www.everylist.com which allows people to post free
classifieds in their local community. When people post a classified, I send
an email to them confirming the post and telling them how to edit it.

Rather than recieving the message, one of my users recieved a warning that I
had sent an Outlook Express virus. Given that the system is unix using
sendmail, this doesn't seem reasonable. Anyone have any suggestions?

 

You'll have to be more specific. Your probably not sending a 'virus'
unless you are forwarding from a Windows box as a front end. Are you
sending any attachments? Did the user's message read "may be a virus".