Hello, I am new to this forum and i expect solution for what i am here. Thx I have front-end and back-end topology in my company using Exchange 2003. Email sending/receiving is working fine through one front-end server but when i change smart host to second front-end server my users couldn't send emails to any external recepient and they are getting following returned message, but they can receive emails but cant send. quote: From: System Administrator Sent: Wednesday, March 02, 2011 4:00 AM To: William Smith Subject: Undeliverable: RE: hiiiiiiii Your message did not reach some or all of the intended recipients. Subject: RE: Hello Sent: 3/2/2011 4:00 AM The following recipient(s) cannot be reached: William Smith on 3/2/2011 4:00 AM You do not have permission to send to this recipient. For assistance, contact your system administrator. <back-endserver.mydomainname.com #5.7.1 smtp;550 5.7.1 Unable to relay for anyemail@gmail.com > I have ISA 2006 istalled on both front-end servers, same publishing rules and same other settings, don't know wheres wrong and whats has been changed which is causing this problem..Please help? Thanks

Check this maybe it will help: http://support.microsoft.com/kb/304897 Additionally under Virtual Server SMTP check Relay settings if using smart host check this: http://www.dnsexit.com/support/mailrelay/exchange/setup.htmWith kind regards Krystian Zieja http://www.projectnenvision.com Follow me on twitter My Blog