> 220 FBCMCL01B06.fbc.local Microsoft ESMTP MAIL Service, Version: > 6.0.3790.3959 ready at Sun, 22 Nov 2009 01:02:20 +0100 I'm confused. This seems to be running MS mail server - what does that have to do with Centos? You've got 2 boxes? 1 is a MS mail server and the other is Centos? Is sendmail running on Centos? Are you sure it is running? Is this the system from which you attempted to send mail? How did you attempt to send it? Did you check the "mailq" command on that system? Does that system have a public IP? Or is it behind a firewall? -- “Don't eat anything you've ever seen advertised on TV” - Michael Pollan, author of "In Defense of Food"