We have Windows 2K with Exchange @K + service pack2 installed i am facing problem when sending mail to @anydomain.net . I receive the following message " There was a SMTP communication problem with the recipient's email server. Please contact your system administrator. <main.acbc.com.eg #5.5.0 smtp;500 Syntax error, command unrecognized>" in general where can i find detail discription for each error hope any one can guide thanks may