ummmm… this is not new. It has been out there for a long time. There may be a new variant of the attached virus, but the actual Hallmark (or other name) e-postcard message has been around quite a while. The best thing to do is just block EXE’s and other risky file types.
The ones to watch out for are the other ones that seem more sinister like the FTC or FBI warnings about being prosecuted or arrested. These are often addressed to high-visibility folks who would open the attachment and unleash a trojan that could capture identity information and return it to the attacker(s).
My bad on this, thanks for the catch and the good info. I received an email from a virus mailing list I was on that listed this one as new.