Error sending massive emails

[rhein_onizuka]

Dear All,

I'm new in Zimbra. I've a problem when sending a massive emails number.

Every day, My Office need to send confirmation email about 3000 emails for all customer. But only a half of them received email.

Zimbra shows this :

Apr 18 17:25:09 mail postfix/smtpd[23109]: A042A18C16A: client=unknown[192.168.10.11]
Apr 18 17:25:10 mail postfix/smtpd[3093]: 4F39518C16B: client=unknown[192.168.10.15]
Apr 18 17:25:12 mail postfix/smtpd[23109]: A954418C16A: client=unknown[192.168.10.11]
Apr 18 17:25:16 mail postfix/smtpd[23109]: B2C2018C16A: client=unknown[192.168.10.11]
Apr 18 17:25:17 mail postfix/smtpd[3093]: C579018C16A: client=unknown[192.168.10.15]
Apr 18 17:25:19 mail postfix/smtpd[23109]: too many errors after RSET from unknown[192.168.10.11]
Apr 18 17:25:19 mail postfix/smtpd[23109]: disconnect from unknown[192.168.10.11]
Apr 18 17:25:22 mail postfix/smtpd[3093]: C980618C16A: client=unknown[192.168.10.15]
Apr 18 17:25:22 mail postfix/smtpd[3093]: DED9B18C16A: client=unknown[192.168.10.15]
Apr 18 17:25:26 mail postfix/smtpd[29517]: connect from unknown[192.168.10.11]
Apr 18 17:25:26 mail postfix/smtpd[29517]: A57D618C16B: client=unknown[192.168.10.11]
Apr 18 17:25:26 mail postfix/smtpd[29517]: AFFFA18C16B: client=unknown[192.168.10.11]
Apr 18 17:25:26 mail postfix/smtpd[29517]: B981718C16B: client=unknown[192.168.10.11]
Apr 18 17:25:26 mail postfix/smtpd[29517]: BE37F18C16B: client=unknown[192.168.10.11]
Apr 18 17:25:26 mail postfix/smtpd[29517]: C36C918C16B: client=unknown[192.168.10.11]
Apr 18 17:25:26 mail postfix/smtpd[29517]: C847E18C16B: client=unknown[192.168.10.11]
Apr 18 17:25:26 mail postfix/smtpd[29517]: D234A18C16B: client=unknown[192.168.10.11]
Apr 18 17:25:26 mail postfix/smtpd[29517]: D717518C16B: client=unknown[192.168.10.11]
Apr 18 17:25:26 mail postfix/smtpd[29517]: DB1C518C16B: client=unknown[192.168.10.11]
Apr 18 17:25:26 mail postfix/smtpd[29517]: E0C3A18C16B: client=unknown[192.168.10.11]
Apr 18 17:25:27 mail postfix/smtpd[29517]: 339E618C16B: client=unknown[192.168.10.11]
Apr 18 17:25:27 mail postfix/smtpd[29517]: 3D6E418C16B: client=unknown[192.168.10.11]
Apr 18 17:25:27 mail postfix/smtpd[29517]: 5C70C18C16B: client=unknown[192.168.10.11]
Apr 18 17:25:27 mail postfix/smtpd[29517]: 65DE618C16B: client=unknown[192.168.10.11]
Apr 18 17:25:28 mail postfix/smtpd[3093]: 469BD18C16A: client=unknown[192.168.10.15]
Apr 18 17:25:30 mail postfix/smtpd[29517]: 3633518C16B: client=unknown[192.168.10.11]

I'm Using Zimbra 6.0.8 on Debian 5 Lenny

Is any configuration in the server or Postfix Tuning ? Or something?


Thx