'571 Mail Relay Is Not Allowed' error E-Double 29.09.2006 19:05:01 For some reason, several Outlook 2003 users keep receiving the following error message when sending emails: "The Following Recipients Could Not Be Reached, someuser[ at ]somedomain.com on 09/29/2006 2:44PM, 571 Mail Relay Is Not Allowed." This is when sending emails thru the regular, local email server and to known users in the address book. The error message pops-up immediately when trying to send, seemingly before it would have time to even attempt to hit the remote or even local email servers. These errors just started about three or four weeks ago with the few Outlook users but never seem to occur with the Outlook Express users. TIA for any help on this one.