This letter informs a company about a potentially libelous or slanderous piece of information that you have seen.
1234, Main Street
Boston, MA 02123
31 March, 2005
<Recipient Address Goes Here>
I have been a customer of <company name> for <time you've been a customer>. Because I like your company and the <products/services> you provide, I feel it's my duty to inform you about the dangerous, potentially illegal levels of pollutants coming from <pollution source>.
I thought I should inform you of this problem, which could, at the very least, get you slapped with a serious fine. It's possible that your people may not even be aware that their actions are <description of actions>. Please take any action necessary to terminate this polluting activity, and feel free to contact me if you need further information. Thank you.
encl: <List of enclosed items goes here>