Selective External Mail Delivery Failure

[emmaylots]

2008-06-18 11:55:01 - mail --> mail.accepted.co.za (192.168.5.28]:2) status deferred
(conversation with mail.accepted.co.za[192.168.5.28] timed out while receiving the initial server greeting)

The is an example of the error log I recieved, when I did a msgtrace -s user@domain.
Every other domain accepts mails from the Zimbra server.(e.g yahoo, hotmail, gmail e.t.c)
I then decided to use our existing Exchange server as an SMTP relay, and our mails get delivered.
The recipient domain uses Exchange server.
What is the problem?

[jholder]

site:zimbra.com/forums +"[SOLVED]" "timed out while receiving the initial server greeting" - Yahoo! Search Results

[emmaylots]

Thanks,
I've gone through the posts.
They appear to have a much different issue.
Mails only get defered only when they are sent to this particular domain.
??

[jholder]

Listen-
There just isn't enough information there to diagnose the error. please post your log files.