A computer-implemented method comprising: receiving a message addressed to a recipient, the recipient being a user of a social networking system; determining an affinity between the sender and the recipient based on information describing interactions in the social networking system between the sender and the recipient; selecting, based on the affinity between the sender and the recipient, a messaging channel from a plurality of messaging channels for delivering the message to the recipient; and delivering the message to the recipient via the selected messaging channel; wherein a messaging server comprises a user datastore, a messaging module, and a graph information datastore, wherein the user datastore stores various types of information about the users of the system, including historical information about a user's past messaging activities, wherein the graph information datastore represents the users of the user datastore as node objects that are linked together in a social graph, wherein the graph information datastore comprises information about the relationships between the node objects, represented as edge objects connecting the various node objects, wherein the social graph is used to keep track of different types of nodes and edges as interactions and connections among those objects, thereby maintaining a store of socially relevant information, wherein the act of sending a message is an edge between two nodes, which is stored and tracked by the social networking system, so that from the social relationships represented by the edges of the social graph, an affinity is determined that indicates the strength of a relationship between two users; wherein the affinity between sender and recipient refers to the social relationship between sender and recipient as determined from the information in the social graph that includes interactions between sender and recipient in the social networking system; wherein some messaging channels, such as SMS, are considered more personal and are only available between users that have a strong affinity with each other, so that the likelihood of selecting an SMS channel is increased if there is a strong affinity between sender and recipient of a message. receiving a message addressed to a recipient, the recipient being a user of a social networking system; determining an affinity between the sender and the recipient based on information describing interactions in the social networking system between the sender and the recipient; selecting, based on the affinity between the sender and the recipient, a messaging channel from a plurality of messaging channels for delivering the message to the recipient; and delivering the message to the recipient via the selected messaging channel; wherein a messaging server comprises a user datastore, a messaging module, and a graph information datastore, wherein the user datastore stores various types of information about the users of the system, including historical information about a user's past messaging activities, wherein the graph information datastore represents the users of the user datastore as node objects that are linked together in a social graph, wherein the graph information datastore comprises information about the relationships between the node objects, represented as edge objects connecting the various node objects, wherein the social graph is used to keep track of different types of nodes and edges as interactions and connections among those objects, thereby maintaining a store of socially relevant information, wherein the act of sending a message is an edge between two nodes, which is stored and tracked by the social networking system, so that from the social relationships represented by the edges of the social graph, an affinity is determined that indicates the strength of a relationship between two users; wherein the affinity between sender and recipient refers to the social relationship between sender and recipient as determined from the information in the social graph that includes interactions between sender and recipient in the social networking system; wherein some messaging channels, such as SMS, are considered more personal and are only available between users that have a strong affinity with each other, so that the likelihood of selecting an SMS channel is increased if there is a strong affinity between sender and recipient of a message.