Hi Firstly can I say what a great contribution. However, I have installed it - 1.4 on an almost vanilla install (1.38a)and ran into some problems with both the HTML preview and the resend

For the html preview I was seeing all the css formatting due to an incorrectly closed style tag. A bit of digging also reviled several other html tags not being correctly dealt with in the translation for the way all the > and < are stored in the database (eg _TAG ParametersOptional _ text _/TAG_ ) and the subsequent display

the lines
PHP Code:
        //$html_content = str_replace('__','><',$html_content); 
        
$html_content str_replace('_html','<html',$html_content);
        
$html_content str_replace('_meta','<meta',$html_content); //DSA
        
$html_content str_replace('_style','<style',$html_content); //DSA 
and various others in the same section (div, table etc) were missing bits of the _ to < or > conversion.
To get my emails to display properly I had to add other tags like UL and TH to the list of $html_content replace statements. That should sort out a few of the preview problems that others have reported.

For the resend I realised that it needed to go through a similar process as for the display. It would be easy enough to make that whole conversion a function and add it to the resend. The thought of all the other possible html tags that would need decoding was tooo much, so at that point I decided to make a very small tweak to the includes/functions/functions_email.php file and not sanitise the storage of the html and store it as it was sent out. Then the resend could use a very simple email_template_archive.html file and the resend works a treat for html emails. This also means the resent emails are recorded in the archive - which someone was asking about