It is against Swap Policy to use the Private Messaging function for sending bulk unsolicited messages - personal or business.
Garnering email addresses from Swap ads, forum posts, or the profile area in order to use them for personal or business mailings is not allowed.
Members wishing not to receive private messages may do so via their User Control Panel at the upper, left of the forum. Click on Board Preferences, choose Edit Global Settings, and set Allow Users to Send You Private Messages to "no".
Members may not currently block messages from a specific individual, although a board modification will eventually be installed to make that possible. Until then, members are prohibited from messaging someone who has asked them not to.