Best email attachment anti-virus?

[NicholasReed]

What do you think is the best product/scanner/antivirus that works on email attachments?
Why is this your choice?
How do these usually work? with similar signatures than what a PC antivirus works? Are these aided by Machine Learning? Why can' they just do Dynamic Analysis on the attachment if time is not that crucial?

[Digerati]

Any decent anti-malware solution will scan attachments. Just keep Windows and your security current.

MailWasher does not scan attachments because it does not download them nor does it need to. Once MW and the user determine an email is legitimate they the user decides to download it, then your security solution can scan it.