♣ 인증 설정 확인

   : telnet local host 25

   : ehlo localhost

     250-coffee Hello localhost.localdomain [127.0.0.1], pleased to meet you
     250-ENHANCEDSTATUSCODES
     250-PIPELINING
     250-8BITMIME
     250-SIZE
     250-DSN
     250-ETRN
     250-AUTH GSSAPI DIGEST-MD5 CRAM-MD5 LOGIN PLAIN <== 인증 설정 OK
     250-DELIVERBY
     250 HELP

♣ 메일 발송 테스트

    : telnet localhost 25

    : mail from : xxxxxx@naver.com
      250 2.1.0 xxxxx@naver.com... Sender ok
      rcpt to: xxxxx@naver.com
      250 2.1.5 xxxxx@naver.com... Recipient ok
      subject: sendmail test
      500 5.5.1 Command unrecognized: "subject: sendmail test"
      data
      354 Enter mail, end with "." on a line by itself
      This is testing mail for sendmail.
      .
      250 2.0.0 pBS8kMQY028068 Message accepted for delivery
      quit
      221 2.0.0 coffee closing connection

    : /usr/lib/sendmail -v xxxxx@naver.com < /dev/null