Linux Mail Server Setup and Howto Guide

Hi consultant,

           I have configured vaction response previously it works fine but now i am trying to configure it but its show like this in /var/log/maillog

Oct 25 15:13:44 mail postfix/smtpd[4789]: NOQUEUE: reject: RCPT from mail.localhost.com[172.26.21.67]: 450 4.1.8 <test@vacation.invalid>: Sender address rejected: Domain not found; from=<test@vacation.invalid> to=<ten@localhost.com> proto=SMTP helo=<mail>
Oct 25 15:13:44 mail postfix/smtpd[4789]: lost connection after RCPT from mail.localhost.com[172.26.21.67]
Oct 25 15:13:44 mail postfix/smtpd[4789]: disconnect from mail.localhost.com[172.26.21.67]
Oct 25 15:13:44 mail Vacation: Orig-To:  From:  MessageID: RCPT TO: error (450 4.1.8 <test@vacation.invalid>: Sender address rejected: Domain not found)
Oct 25 15:13:44 mail Vacation:  Subject:
Oct 25 15:13:44 mail postfix/pipe[4814]: 9458C23656E: to=<test@vacation.invalid>, relay=vacation, delay=2.5, delays=0.26/0.14/0/2.1, dsn=2.0.0, status=sent (delivered via vacation service)
Oct 25 15:13:44 mail postfix/qmgr[4506]: 9458C23656E: removed

      Please gulde me to solve this problem.