It seems as if email spammers have found a workaround to trick both the virus scanner and spam filters of Gmail.
I have got at least three different mails in my Gmail account today that carry virus attachments but they still managed to reach the inbox just like other regular mails.
Looking at the file name (mywifepics.zip), it was fairly obvious that the attachment is a virus and Windows Defender too helped confirm the same as some Win32/Wmfap exploit.
Why you get Virus Infected mails in Gmail
Now the reason why these infected zip attachments could trick Gmail so easily is because they were password protected and Gmail scanners cannot read contents of such files. What’s surprising though is that even the spam filters of Gmail failed to catch these messages.