Gmail has been a pretty strong spam blocker so far, and I use it to route emails to avoid webmail spam for our other email ids too, but there have been some lapses on their part where International characters (non English) are concerned.
I received a email at my Gmail account, which had a rar file attachment, but for some reasons Gmail showed a message saying Gmail Could Not Scan This File For Viruses.
My first reaction to the email was that probably Gmail did not scan some types of file, but I sent out a test email with a similar file type, to see whether Gmail would scan the file or not, but it did scan the file.
As you can see it was actually able to scan my attached file for viruses, I am still clueless as to why Gmail was not able to scan the file attachment in the earlier email.
I have the base64 attachment from the email and will run it though some checks and investigate the problems and update our readers shortly. The next time you want to download any attachments, make sure it has been checked for viruses by Gmail itself.