[Dovecot] Sieve & Regex

[Peregrino "Pipino" Tuc]

Hi all
I'm trying to create a new sieve rule.

What I would like to do is catch "From" addresses that
are equal to the rightpart (hostname) of a message-id.

For example:

Message-ID: <000d01c9d23a$941a7db0$6400a8c0 at upwabm>
From: "Leanne Crabtree" <upwabm at blomberg-co.com>

I would like to catch this mail, because it has
"upwabm" on the right part of the message-id and
"upwabm" on the left part of the sender address.

I've done this, but with no success. The error
reported is: "Invalid preceding regular expression"
on line with the second regex with ${1}

More over I would like to add an header with the
result of regex, an header like this:

"X-MyHeader" "${1}" but it does not work.

This is an extract of our sieve:
---
require ["regex"];
if header :regex "Message-ID" "^.*@(.*)>$" {
   if header :regex "From" ".*<${1}@.*>$" {
      addheader "X-MyHeader" "${1}"
   }
}
---