My company is using GFI MailSecurity for Exchange/SMTP 8 now.
We have tested GFI MailEssentials for Exchange/SMTP.
They work like they say they do. They give us very little trouble.
It seems like the products from GFI are getting better.
I wouldn’t say they are perfect. http://kbase.gfi.com/showarticle.asp?id=KBID001840
They are building a knowledge base which is helpful.