Exchange 2003 internal and external mail issues

Dear all,

I have some serious issues with our email. I would be very happy to have a bit of help because I don’t really know where to start. This is the configuration:

MS Win 2000 Server SP4 and update roll up 1, with Exchange 2003 SP2 version 6.5.7650.28, one server in backend, one in frontend configured.

Installed software: Symantec Information Foundation Mail security 6.0 with premium anti spam.

Maybe this is also important info: My inbound and outbound WAN IP address are different. Although both addresses are fully reversible to their host names, some mail servers complain about this configuration. Some examples of NDR’s:

here was a SMTP communication problem with the recipient’s email server. Please contact your system administrator.

Action: failed
Status: 5.5.0
X-Supplementary-Info:
X-Display-Name: name@emailaddress.com

name@hotmail.com on 22/08/2007 2:30
There was a SMTP communication problem with the recipient’s email server. Please contact your system administrator.

You do not have permission to send to this recipient. For assistance, contact your system administrator.
… Relaying denied. IP name possibly forged [123.123.123.123]>

This is an automatically generated Delivery Status Notification

Delivery to the following recipient failed permanently: name@emailaddress.com
Technical details of permanent failure:
PERM_FAILURE: SMTP Error (state 13): 554 : Relay access denied

For some non-delivered email no NDR is received at all. Does this mean that the anti spam of the recipient’s SMTP server deleted the message? Would it be a good idea for solving the external mail issues to have both inbound and outbound server on the same IP address?

The last week I had also internal mail problems. One user could send an email with attachment to one particular user, the other recipients within our company have no problems receiving her mail. The particular recipient receives the mail, but without the attachment. No user-specific exchange options were changed, all settings are default… Another user reported that she did not receive internal messages at all.

Symantec’s software has configuration which excludes email, spam and content filtering for internal mail.

I know it’s a lot but I would be very happy if already a tiny bit of my issues would be resolved.

Kind regards,

G?nther a