Hi AllI want only my domain users can send mails through my Exchagne Server, and not allow any other user to just put the IP Address of the SMTP Server and send through My Exchange.I tried to searched about something like SMTP Authentication, but I only can find how to restrict the IP Addresses that are allowed to relay through the Exchagne Server.Plese guide me to the link to how do it.

Hi Alaay,1. Open Exchange System Manager2. Expand Server/Your Servername/Protocol/SMTP3. Right Click Default SMTP Server and select Properties4. Click on the Access tabUnder relay restrictions, you will see that you can grant/deny relay permissions. The Exchange Server IP should be the only one on that list and "only the list below" should be checked off.You can alsoallow authenticated users to send "Allow computers that successfully authenticate...". This will allow mobile devices that communicate through pop3/smtp and thrird party mail clients to connect and relay, so long as they provide credentials.If you have had an open relay, please see this article to help you clean up the queuehttp://technet.microsoft.com/en-us/kb/kb00324958.aspxCheers,MiguelMiguel Fra / Falcon ITS Computer and Network Service and Support, Miami, Fl

By Default Exchage wont allow to relay emails from any smtp client it has to be authenticated by Exchange server. and below article provided by the Friend should be useful to make sure you are not running your server as open relay which will allow any client to send email without any authentication.Vinod |CCNA|MCSE 2003 +Messaging|MCTS|ITIL V3|

Hi,Check the below article:http://www.petri.co.il/preventing_exchange_2000_2003_from_relaying.htmThanksAllen