Generating emails from a site

If I want to allow people to collect comments and forward those comments via email to an email address of their choice showing their email address as the from address, what are the legal and business implications of that, if any? The email will be generated by my site and I will not control the content of the email that is sent, other than to scan for obvious controversial words.


First thing to do would be having a consent from the original posters, if they are ok with such thing. Other then that I dont think there would be any problem.
Many classified sites do such things for years now.

Thanks for the input. I will include a checkbox to get their permission for their post to be forwarded.