I user with email address ahcs@ahcs.com.au . he cannot receive email send to Ahcs@ahcs.com.au. My question is IS exchange 2007 emails are case sensitive and if yes then is there any solution so that user can receive email sent to both ahcs@ahcs.com.au and Ahcs@ahcs.com.au.

It is not case sensitive. You need to provide more information about your EX configuration. What error message are you getting? Santhosh Sivarajan | MCTS, MCSE (W2K3/W2K/NT4), MCSA (W2K3/W2K/MSG), CCNA, Network+ Houston, TX http://blogs.sivarajan.com/ http://publications.sivarajan.com/ This posting is provided "AS IS" with no warranties, and confers no rights.

Does the sender receive any NDR for user AHCS? Does the mail flow only happen to user AHCS? Whether the address is the primary or secondary address for user AHCS? Is the ahcs.com.au an authoritative domain on the exchange 2007? Please use the message tracking log to check the mails to user AHCS The protocol logging records on the receive connector will also help for the troubleshooting How to Configure Protocol LoggingJames Luo TechNet Subscriber Support (http://technet.microsoft.com/en-us/subscriptions/ms788697.aspx) If you have any feedback on our support, please contact tngfb@microsoft.com