How do i prevent this kind of spam

[codehaxor]

I have users complaining that they receive Spam Email coming from their own email address like for example:

mary who's email address is mary@blah.com

receives email from her own email address which is mary@blah.com, but she didnt write the email herself.

i think this has got something to do with ehlo or something, can anyone show me the settings on how to prevent this kind of attack

[ScalixSupport]

Please refer to Scalix administration guide's spam and anti-virus section.

Cheers,
Yuri