Hi All.
i have spent alot of time looking into this issue but none of the answers on here apply to me.
so recently i imported some mail for a domain all went smoothly eventually and ever since that point i havent been able to recieve email for my other domain.
when i send email to it i get the following.

this is when i send an email to user@domain.net

Code:
This is the mail system at host mail.domain.net.
 
I'm sorry to have to inform you that your message could not
be delivered to one or more recipients. It's attached below.
 
For further assistance, please send mail to postmaster.
 
If you do so, please include this problem report. You can
delete your own text from the attached returned message.
 
                   The mail system
 
<user@domain.net>: domain.net
after i restart the services some times i get a 5.5.2 error but that doesn't stay there long.
i am at a loss as to what is going on, seen as two other domains work fine.
i have checked my reverse lookups and they are all set correctly.

postfix says this

Code:
Mar 31 13:21:33 mail postfix/smtpd[399]: connect from icp-osb-irony-out6.external.iinet.net.au[203.59.1.222]
Mar 31 13:21:33 mail postfix/smtpd[399]: NOQUEUE: filter: RCPT from icp-osb-irony-out6.external.iinet.net.au[203.59.1.222]: <sender@otherdomain.net>: Sender address triggers FILTER smtp-amavis:[127.0.0.1]:10026; from=<shaun.oconnor@vizstone.com> to=<user@domain.net> proto=ESMTP helo=<icp-osb-irony-out6.external.iinet.net.au>
Mar 31 13:21:33 mail postfix/smtpd[399]: NOQUEUE: filter: RCPT from icp-osb-irony-out6.external.iinet.net.au[203.59.1.222]: <sender@otherdomain.net>: Sender address triggers FILTER smtp-amavis:[127.0.0.1]:10024; from=<sender@otherdomain.net> to=<user@domain.net> proto=ESMTP helo=<icp-osb-irony-out6.external.iinet.net.au>
Mar 31 13:21:34 mail postfix/smtpd[399]: DE64A178063: client=icp-osb-irony-out6.external.iinet.net.au[203.59.1.222]
Mar 31 13:21:35 mail postfix/cleanup[406]: DE64A178063: message-id=<0FAD44F7BA9BC94B83C51D624EF27E09BC3740@server.company.local>
Mar 31 13:21:35 mail postfix/qmgr[29710]: DE64A178063: from=<sender@otherdomain.net>, size=2576, nrcpt=1 (queue active)
Mar 31 13:21:40 mail postfix/smtpd[399]: disconnect from icp-osb-irony-out6.external.iinet.net.au[203.59.1.222]
Mar 31 13:21:58 mail postfix/amavisd/smtpd[29722]: connect from localhost.localdomain[127.0.0.1]
Mar 31 13:21:58 mail postfix/amavisd/smtpd[29722]: 879DF178065: client=localhost.localdomain[127.0.0.1]
Mar 31 13:21:58 mail postfix/cleanup[406]: 879DF178065: message-id=<0FAD44F7BA9BC94B83C51D624EF27E09BC3740@VIZ-DC-EXC02.vizstone.local>
Mar 31 13:21:58 mail postfix/qmgr[29710]: 879DF178065: from=<sender@otherdomain.net>, size=3354, nrcpt=1 (queue active)
Mar 31 13:21:58 mail postfix/error[417]: 879DF178065: to=<user@domain.net>, relay=none, delay=0.3, delays=0.02/0.13/0/0.16, dsn=5.0.0, status=bounced (domain.net)
Mar 31 13:21:58 mail postfix/cleanup[406]: D218E178068: message-id=<20130331172158.D218E178068@mail.domain.net>
Mar 31 13:21:58 mail postfix/bounce[418]: 879DF178065: sender non-delivery notification: D218E178068
any help would be greatly appreciated.

Thanks