The AddressBlockAdd function is used to add to the set of destinations which are blocked on an EasyLink system. The EasyLink 'XDDS' system (used for fax, voice and simple email) and 'MR' system (used for enhanced email and SMS) maintain separate sets of blocked destinations.

Note that this function is generally available to API users. However, the companion function, AddressBlockDelete is available only by special permission.

Address blocks are commonly associated with a response to a particular message delivery job, and several fields are available to record job information as a way to record the origin of the block.