Email not being received from a certain client from Germany

Just try to put the address of your client on the white list so it is not considered as spam.

Tried this no good, dont really understand what this message means or indicates what the problem is

Install software again and use the white list feature to add the e-mail of your client on the white list. A white list is a list of e-mail addresses that e-mail server trust.

Is there an anti-spam appliance that accepts/filters incoming email and forwards that email to the email server?

Have installed software again and white listed the whole domain and email, still no luck. There is no anti-spam appliance that accepts/filters incoming email.

I asked the client if any changes have been made on their end and the said that they had changed providers but have had
had no other issue with other people.

Do you think it might be domain record related e.g TXT, PTR record related on our end, would that likely be the reason why the provider might be reject our server ?

From the sounds of it the message #< #4.4.2 X-Postfix; lost connection with mail.ihs-aust.com.au[202.45.112.211] while sending MAIL FROM> #SMTP# indicates that it is getting to us but being cut off or rejected at our end. I have checked everything I can think off and have sent at least 10-15 emails from different providers and all have come throught to us. Have checked, Spam Block lists and even done DNS tests via DNSSTUFF.COM.

I cant seem to get enough information regarding the message to be able to track down further.

on the server:

grep smtp_helo_name /etc/postfix/main.cf

what do you have set?

is this command for linux we have a windows SBS 2003 server

yes but i would expect that you have the same configuration file.  can you look at it?

Yes I will and post back results

That I cannot help with.  You should probably have a moderator ping an Exchange expert.

Issue still not resolved at this stage still working on will update this once i find solution

Jim