It's a test if you aren't running an open proxy. Its purpose is antispam.
On Thu, 11 Dec 2003, An Metet wrote: > I have noticed this lately: > > When someone sends mail to [EMAIL PROTECTED] , shortly thereafter a query comes from > the ISP that runs the outgoing SMTP and loads http://www.thisdomain.com. > > The query does not load any images, just the base html page. It comes from IP > usually in the same cloud as outgoing SMTP. > > Sometimes this happens only after the first mail from that ISP to thisdomain.com, > sometimes every time. > > Is this anti-spam (why querying the recipient?), or some data harvesting and > connecting the dots?
