IceWarp 메일서버 중 SMTP 데몬의 5로 시작하는 오류코드입니다. 코드 상세코드 오류 설명 문제해결 가이드 500 5.5.1 Command unrecognized The SMTP command currently used was unrecognized or is not supported by the SMTP service. Review the syntax of the last command and try again. Another possibility is that you are trying to use telnet and the telnet connection to your server is not allowed. Check the settings in administration console: ..