An anonymous reader writes "The small travel agent that I work for recently received an email from one of our competitors with several thousand of their potential customers in the 'To:' and 'Cc:' fields. My boss now wants to use these addresses to send unsolicited advertisements. I would like to convince him not to do this, as I believe that this practice is morally wrong and legally dubious. However, morals don't go very far in the business world, so I'm asking Slashdot: what business-oriented arguments can I use to dissuade my boss from spamming?"