Differences between SMTP gateway and Exchange VSAPI mode

The main differences between the SMTP gateway mode and the Exchange VS API version of GFI MailSecurity are as follows:

SMTP Gateway version only scans inbound and outbound mail, not internal mail
SMTP Gateway version has more information about the e-mail, and can therefore quarantine outbound mail without the need for a ticketing system
SMTP Gateway version has more information about the e-mail and can therefore determine better if it's an inbound or an outbound mail.
SMTP Gateway version has a more advanced quarantining system. It is possible to hold the entire email until a part is approved or rejected - that way a recipient only receives the mail if it is approved. He will receive the mail in its entirety.
Exchange VS API version can only be used on Exchange 2000/2003
Exchange VS API version can scan internal mail also, and can therefore prevent internal virus outbreaks.