Hi and thanks for using ReDJ.
Problem here is you can't use pathltrim macro, because the /Newsletters/newsletter-name-1.html is just a parameter (appears after index.php).
So, you could get the part you need newsletter-name-1 using preg_match, but this is only available in the Enterprise version:
From URL: /index.php\?/Newsletters/
To URL: http://{siteurl}/resource-center/newsletters-archive/{preg_match 1}/\/Newsletters\/([^\.]+)\.html/{/preg_match}
This should work.
Best regards,
Luigi