Check with ISP MX records not configured correctly it is not pointing your mail server it is resolving to wrong IP number....
-----Original Message----- From: Albert Vasquez [mailto:[EMAIL PROTECTED]] Sent: Thursday, October 18, 2001 9:18 AM To: MS-Exchange Admin Issues Subject: Exchange 2000 problem....can't receive mail... We have an Exchange 2000 server running... it can send mail but it can't receive mail... this is the error that I get.. Oct 17 21:06:48 na sendmail[13107]: f9I0vfF12422: to=, ctladdr= (500/500), delay=00:09:07, xdelay=00:00:01, mailer=esmtp, pri=21182674, relay=xxxx.xxxx.xxx. [xxx.xxx.xxx.xxx], dsn=4.0.0, stat=Deferred: 454 5.7.3 Client was not authenticated. Any ideas? AlV List Charter and FAQ at: http://www.sunbelt-software.com/exchange_list_charter.htm List Charter and FAQ at: http://www.sunbelt-software.com/exchange_list_charter.htm