i finally implemented an email button on my web site after what... three to four years?
it's a python JSON service (http://lkcl.net/site_code/ - see json_service directory)
unfortunately, mod_python won't let me import smtplib for some reason, so i had to use popen2 on /usr/bin/mailx. oops.
you'll need the slightly modified version of jsonrpc (also in the json_service directory). you'll need to put json_service/email.py into a services subdirectory (e.g. /var/www/services). you'll need to create /var/cache/mailsender and chown www-data:www-data it. and you'll need this in apache config:
<Directory /var/www/services > AddHandler mod_python py PythonHandler jsonrpc.apacheServiceHandler PythonPath "sys.path+['/usr/share/python-support/python-simplejson/simplejson/']" </Directory>