Hostname shown twice in post url rewrite path = 404 error

Server Config
3

This is what seems to have finally resolved the matter:

RewriteEngine on
RewriteBase /newsletter/activate/
RewriteRule ^subscription/x/(.*)/y/(.*)/?$ process.php?x=$1&y=$2 [L]

It works in the sense that there is no repeated host name in the rewritten URL, and process.php receives the variables and processes them without a hitch.

Thought this might be of interest.

Thank you very much for the time and ideas.

~ David