Visitor Messages And V7N Private Messages (PMs)
First it is important to know the difference between the two. If you leave a visitor message, it is viewable to anyone looking at that members profile. If you intended for the note to be private, you should choose the contact info tag on their profile and click to send a private message. This option can also be found in a drop down menu when clicking on a member's user name in a thread.
Neither of these methods of contact may be used to spam unsolicited information.
If someone does not specifically ask you to contact them with information about your product, service, site, etc., to do so is flat out spam and you will be banned. It is as simple as that.