If you enable this option, the program adds a business card to your message that does not give away your name or e-mail address.
When you write in a Group of a very well known service, that service always adds advertisements to your messages. As of yet, these ads can be suppressed by adding a business card to your message and by putting a stationery background in your message.
If the recipient's e-mail address contains '@yahoogroups.com' then a VCard is added automatically.
(For those who work a lot with stationery and scripts, you know how these ads can ruin your work! )