Mystery e-mails...oh, and Virex

[pscates2.0]

This is a two-part question (but they may be related):

1. Starting about three or so days ago, I've been getting "blank" e-mails to Mail.app. They have an arrival date, but there is no sender shown and no subject. I clicked on the first couple, out of curiosity, and no message. What are these?

2. Tiger was, I believe, incompatible with Virex (it was removed from .Mac). I know that, compared to Windows, Macs are relatively virus-free. But still, back during Panther, I'd run Virex and things would be found. Since installing Tiger, I've done nothing on that front. Am I riddled with virus and whatnot?

Help/answers with either are greatly appreciated. :)

[LudwigVan]

Can you view the complete header of those messages in Mail? There may be an IP address or similar clues that won't appear on the user friendly "short" header display.

[torifile]

I've gotten those lately too. I don't think there's actually anything *in* them because I've got the message size shown and they're .5kb when a message with just a little text is often 1.5kb or larger. I just hit "junk" when my junk mail filter doesn't catch 'em. I can't imagine that they're dangerous in anyway, even to a windows computer. A virus has to be in the email for it to do anything...

[FFL]

yeah, I've been seeing these for a while, and they seem to have increased lately.

my theory is that they are "verifying" addresses for spam lists. if they don't get an "invalid address" bounce from your ISP, then your address checks out.