I was happy beacuse new feature of v4.2.3.03 firmware, the Email LOG feature.
After testing this feature I recongnized, sending Email work in a way where RV first try to ping (ICMP ECHO) Mail Server if it is not respond, then break sending email.
In a real word to save resources ping response feature of mail server always disabled. Therefore RV's Email feature cannot work in a real word.
Anybody has idea how possible to workaround this problem?