1. A method for sharing content between users of different social networks, the method comprising: in a source social network implemented by at least one processor, receiving shared content with an indication of a number of recipients of the shared content, wherein the shared content and the indication of the number of recipients of the shared content are part of a single message, wherein said shared content with said indication of said number of recipients is uploaded by a source user, and wherein the source user defines access rights for one or more of the recipients indicating whether the corresponding recipient has edit rights or read-only rights for the shared content; storing the shared content and identifying information for each of the recipients on the source social network; generating a navigating link which is provided to the recipients and directs the recipients to a location of the shared content on the source social network; establishing a trusted communication link between the source social network and at least one external social network, wherein the source social network will authenticate received credentials of the at least one external social network and conditionally grant access to the shared content based on authenticity of the credentials of the at least one external social network requesting access; in addition to authenticating credentials of at least one external social network, authenticating a user requesting the shared content as being one of the designated recipients; enabling an authenticated requested user to retrieve the shared content from the source social network using the at least one external social network via the trusted communication link according to the defined access rights of the authenticated requesting user; and maintaining metadata about the authenticated requesting user at the source social network, wherein metadata regarding access of the shared content is appended to the metadata for the authenticated requesting user.