Relay denied

[nick]

Hi, Can anyone help me....

Im having probelms sending mail from a client machine through FC3.
It was working before on a 192.168.X.X address

Since I changed the FC3 box it to a different fixed ip address
172.16.1.36 and made changes in the access file too using the the
relay address 172.16.1.0 and restarted the box.. I cannot send out
mail anymore, can please someone talk me through what i need to do to
get it working..

This is the error message i get for outloox

Your message did not reach some or all of the intend recipients.

Subject: Hello
Sent: 25/10/2005 23:15

The Following recipient(s) could not be reached:

'username at xxxxx.com' on 25/10/2005 23:15
    550 5.7.1 <username at xxxxx.com>... Relayed denied. IP name possibly
forged [172.16.1.33]