Hi all is easy to run it on 1.4.2 :
unzip exention / open it / find file : manifest.xml
Open that file with Notepad++ for eg and found the line on start :
<minversion>1.3</minversion>
<maxtestedon>1.3.4</maxtestedon>Change "1.3.4" with "1.4.2" and save the file.
Upload the folder on your "extensions" folder trought FTP
Go on your admin pannel and instal this "extension".
You are done - it work fine.
@JoeySnacks :
Loading of extension "pun_admin_broadcast_email" failed.
Missing manifest.xml.
It's because you unzip bad - open the unziped folder you will found a other folder called "pun_admin_broadcast_email" is this one to put on your FTP.