You'll see crap like that in the mail logs from an attempted spam run
through an open HTTP proxy. This is where you've got an open HTTP
and you send it a GET http://destination:25
Better spell it out Sam. "You don't have an open-relay SMTP server, but
*probably* have an open PROXY server". That is *majorly* worse than an
open-relay as it means people can - say - gateway access to your internal
servers via it (that's ANY internal server - telnet, smtp, web, etc)
Fix that proxy server :-)
No. No open proxy here. Actually, no proxy here at all. And that request
originated outside of my network. These lines where definitely errors and no
mail was delivered.
I believe this was just a probe to see if the machine was open. There was
only one request like this and the only result was a few errors in the logs.