[Mailman-Users] mail issue to moderator

[Srinivas Rao Balla]

Hi all,
our production mailman suddenly stopped sending mail to moderator for required list approvals and  subscription approvals.
Ex: when someone scribe to mailing list we have configured to receive the mail to "moderator/administrator" for approval 
but in our case administrator/moderator not getting mails on their mail box. each time we need to logon to list and see for the pending approval or subscriptions  which is not practical.
We are sing "postfix." as mail agent for mailman. Below are the error messages.
/var/log/mailman/smtp-failures

Oct 10 00:45:54 2014 (8899) All recipients refused: {'it-hyd-owner at intra.domain.com': (550, '5.7.1 Unable to relay')}, msgid: <mailman.0.1412927143.9231.it-hyd at intra.domain.com>
Oct 10 00:45:54 2014 (8899) delivery to it-hyd-owner at intra.domain.com failed with code 550: 5.7.1 Unable to relay
Oct 10 00:46:57 2014 (8899) All recipients refused: {'it-hyd-owner at intra.domain.com': (550, '5.7.1 Unable to relay')}, msgid: <mailman.11.1412927205.8897.it-hyd at intra.domain.com>
Oct 10 00:46:57 2014 (8899) delivery to it-hyd-owner at intra.domain.com failed with code 550: 5.7.1 Unable to relay

/var/log/maillo
Oct 10 00:33:39 intra postfix/local[8975]: 8E8FBCE1AE: to=<it-hyd at intra.siliconimage.com>, relay=local, delay=0.2, delays=0.03/0.01/0/0.17, dsn=2.0.0, status=sent (delivered to command: /usr/lib/mailman/mail/mailman post it-hyd)
Oct 10 00:46:45 intra postfix/local[9216]: C81EFC6A8D: to=<it-hyd at intra.siliconimage.com>, relay=local, delay=0.19, delays=0.02/0/0/0.18, dsn=2.0.0, status=sent (delivered to command: /usr/lib/mailman/mail/mailman post it-hyd)


Please help me to to resolve this issue.
Thanks,Bsrao