Verifying valid SMTP senders

[lwolfson]

I have had users put their email addresses in a web site and now they get hundreds of spams. Blocking known spam domains is easy, but I want to be able to block emails at a higher level. How can I get the IMC to verify sender's email domain as valid? When communicating with an Exchange SMTP, I find it quite easy to send spam to an Exchange server with absolutely anything in the Mail from: command. Seems as long as there is a valid rcpt to: smtp address, anything gets through. Any ideas?

Any luck with 3rd party solutions?

 

[Zelandakh]

This was covered about 10 days ago in this forum - something like setting the delivery option to only accept inbound email from your own server.

 

[Mulligans]

I use Mail Essentials and there is actually a button that says "Refuse Mail without FROM in email header". This software is working really well. Not sure if there is a way to do it inside Exchange.