Hi, Users are not able to send external mails while using outlook express but can send external mails using Outlook MAPI client. I am forwarding all external mails to smart host from my backend server. What should I do to allow external mails from internet clients like Outlook express?? I am running exchange 2003 sp1 and sendmail on linux. Regards Praveen R --------------------------------- Start your day with Yahoo! - make it your home page