postfix env variables in header_checks

[Simon Herter]

Hello,

currently I do the following header_checks:
/^Received: by myhostname .*from userid [0-9]+\)/ IGNORE
/^Received: (.*)by myhostname \(Postfix\) (.*)/ REPLACE Reveiced: $(1)by 
myhostname $2

Now I was wondering if it is possible to use actual $myhostname variable 
from postfix config? Something like:

/^Received: by $myhostname .*from userid [0-9]+\)/ IGNORE
/^Received: (.*)by $myhostname \(Postfix\) (.*)/ REPLACE Reveiced: 
$(1)by $myhostname $2

Greetings