Mail not delivered

[ask2me007]

Dear Friends
Iam using
Release 6.0.1_GA_1816.RHEL5_20090911181524 CentOS5 FOSS edition.
The server was workinng fine .But from last week i noticed there are certain mails exists in the mailque.The zimbra log says that

pop postfix/smtp[12398]: 028B913C8006: to=<kxxfxxxx3a@gmail.com>, relay=alt1.gmail-smtp-in.l.google.com[209.85.211.28]:25, delay=36645, delays=34420/1004/601/620, dsn=4.4.2, status=deferred (conversation with alt1.gmail-smtp-in.l.google.com[209.85.211.28] timed out while sending end of data -- message may be sent more than once)

I couldnt find an reason for not sending the mail.The mail has some attachment also.
Pls help me to solve this problem
Thans in advance.

[y@w]

Are you by chance behind a Cisco PIX? Postfix Frequently Asked Questions

[vbn]

Most likely a firewall issue. Try disabling any running firewalls. I encountered same issue and it was solved. Let me see if I can get you a specific solution. Need to remember what I did

[ask2me007]

Presentl m server is behind ipcop firewall and iam using copfilter(addons).I have changed the configuration in ipcop smtp configuration.But iam getting mails to and from through my mailserver.