The mailing list for listmasters using Sympa

[Adam Bernstein <address@concealed>]

> 1) Strip off the HTML part of all posted messages, so that only the text/plain
> part is sent; then append the footer.

You could achieve that by setting everyone's subscription mode to text 
only, and making that the default mode for the list and maybe the only 
available mode.

> 2) Append a text footer to the text/plain version, then somehow insert another
> HTML footer right before he closing body tag in the HTML version (add footer
> here ... </body></html>)

That's the thing, and the reason Sympa doesn't even try to append to HTML 
messages: you don't know that there is going to be a closing body or html 
tag, and in many HTML emails there won't be.  But in some there will.  It 
all depends on what software composes the message, and with all the 
variation and all the possibilities, including the potential for unclosed 
tags of various sorts or for the end of the HTML being some fancy 
formatting block that would affect the footer, there's no guarantee of the 
appended footer looking right or even being visible.

     ab