This library was reported in http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=507947

The license for html2text is not included in the code, but rather on the website of the author:

  http://www.howtocreate.co.uk/jslibs/termsOfUse.html

The most problematic bit of html2text's license is the requirement to get written permission to distribute:

"However, if you want to include the scripts [...] in bundled or distributed scripts/software (such as Opera or Dashboard widgets, or the Formativ Academic Timetable), you should contact me first and obtain my express written permission."

Then, there is a bit of discrimination for commercial sites through the addition of an "advertising clause":

"Commercial/profit-making public websites:

You should put a note saying that the script was provided for free by http://www.howtocreate.co.uk.

You put a plain text (ie. not script) link to my site on your policy page or other appropriate page, to help me with my search engine rankings."

The Debian developer who filed the bug suggested that we take a look at replacing this library with the one I have attached here. It's got the same name but is under the GPLv2+.

Based on a quick 1.9 grep, that file is only used in lib/weblib.php:html_to_text(), which in turn is only used in format_text_email() of the same library file.