We are using exchange 2003 server SP2 in front end and backend configuration. front end is hosted in dmz and back end is placed in internal network.
Mail functionality is working ok for internally as well as externally except for one user. That one user can send and receive email internally but he cannot send mail externally.He can receive mail from externally. outlook 2003 is email client.
That one user has primary smtp address as email@example.com and secondary address as firstname.lastname@example.org. He can receive mail successfully at email@example.com from outside but he is unable to send email to outside domain.
I created new pst for user and I tried by using from field in outlook 2003 but still problem persists.