Usage: messageadd cluid={clientUID} subject={subject} message={text}

Permissions:

Description:
  Sends an offline message to the client specified by cluid.

Example:
  messageadd cluid=oHhi9WzXLNEFQOwAu4JYKGU+C+c= subject=Hi! message=Where\sare\syou?!?
  error id=0 msg=ok
