We have seen quite a lot of variants of this particular trojan recently, mostly aimed at banks. This one passes itself off as a some sort of digital certificate, but according to VirusTotal it is a trojan variously identified as TrojanDownloader:Win32/Suceret.gen!A, Win32.Stration, Trojan-Downloader.Win32.WebDown.10 and a number of other generic detections.
Subject: Better Business Bureaus, Attention: Don't leave mail in your mailbox.
From: "Better Business Bureaus Account Support"
Attention Better Business Bureaus Consumers!
We've enhanced web surfing process with new security measures to keep your online
data and personal information safer.
All registered and new BBB consumers must register new software and update contact
information until October 24, 2008.
Please read the following information carefully:
Register your BBB company certificate here>>>
As always, we appreciate your business. And thank you for working with us.
Sincerely, Ila Newell.
2008 Council of Better Business Bureaus