We keep getting errors in the "system" section of the event viewer on our IIS server. These problems started showing up about 2 weeks ago. We have double and triple checked the configuration of the default SMTP service installed with IIS.<BR><BR>We have tried switching to different DNS servers since some of the messages seem to be DNS related. Sometimes we can switch the DNS setting for TCP/IP properties and a few of the emails will go through BUT then delivery to other domains which used to work then seem to stop. Right now, most email messages ( about 90% ) are not going through at all and end up eventually in the badmail directory.<BR><BR>Here are some example events:<BR>Message delivery to the remote domain 'aol.com' failed for the following reason: Unable to bind to the destination server in DNS. <BR><BR>Message delivery to the remote domain 'aol.com' failed for the following reason: The remote server did not respond to a connection attempt.<BR><BR>Message delivery to the remote domain 'aol.com' failed for the following reason: The connection was dropped by the remote host.<BR><BR>I have already tried searching google and microsoft.com, and have not had any sucess resolving this. Has anyone else encountered this before and is there a solution?<BR><BR>Thanks in advance.