Using Environment variables in configuration settings

[Brad Beckenhauer]

Hello,

Using MS 4.54.6 on Centos 4.3
I'm trying to use an environment variable in the X-settings without
success.
I want to strip off the HOST from the $HOSTNAME and use the results in
the X-tag.

But it appears that I cannot even use $HOSTNAME in the X-tags.

How can I get just the host portion of $HOSTANME in the "X-" header?

Desired:
X-mx2-SpamCheck:

where mx2 is extracted from $HOSTNAME

thanks