501 Connection rejected by policy [7.7] 9413

Hi,

We are having troubles with out outgoing emails to some customers using the messagelabs / symantec system.

Below is an example of the error

cluster6.us.messagelabs.com[216.82.242.36] refused to talk to me: 501
Connection rejected by policy [7.7] 9413, please visit
www.messagelabs.com/support for more details about this error message.

Our mail servers IP address is
188.166.199.86

It is a clean IP address (not blacklisted)
http://mxtoolbox.com/SuperTool.aspx?action=blackli...

We also have a 2nd mail IP which is
128.199.237.162

http://mxtoolbox.com/SuperTool.aspx?action=blackli...

This is also blocked for some reason :(

Are we able to please get these unblocked?

Thank you,

Matt
Wavetech