A computer-implemented method comprising: accessing, by a messaging management service, message recipient information that includes, for each of multiple message recipients, i) preference data identifying one or more messaging services through which messages are to be sent to a user, and, ii) for each of the messaging services through which messages are to be sent to the user, account information for the user; receiving, by the messaging management service and from a message initiator, a message request, wherein the request includes at least i) a message content type identifier that indicates a type of message that is to be transmitted, and ii) data identifying one or more message recipients; for each message recipient: selecting, by the messaging management service, one or more particular messaging services based on the preference data for the message recipient; for each of the particular messaging services: generating, by the messaging management service, a message (127a-c) based on the message content type identifier, transmitting, by the messaging management service, the message (127a-c) and the account information for the user to the messaging service; receiving, by the messaging management service, new messaging service provisioning information for a new messaging service, wherein the new messaging service provisioning information includes: information that associates message content type identifiers to message templates that are formatted for the messaging service, and instructions for electronically communicating messages to the new messaging service; transmitting, by the messaging management service and to one or more message initiators, a notification indicating that messages may now be transmitted through the new messaging service; and receiving, by the messaging management service and from one or more of the message initiators, updated message recipient information that includes, for each of one or more of the multiple message recipients: updated preference data identifying the new messaging service, and account information for the new messaging service and the user. accessing, by a messaging management service, message recipient information that includes, for each of multiple message recipients, i) preference data identifying one or more messaging services through which messages are to be sent to a user, and, ii) for each of the messaging services through which messages are to be sent to the user, account information for the user; receiving, by the messaging management service and from a message initiator, a message request, wherein the request includes at least i) a message content type identifier that indicates a type of message that is to be transmitted, and ii) data identifying one or more message recipients; for each message recipient: selecting, by the messaging management service, one or more particular messaging services based on the preference data for the message recipient; for each of the particular messaging services: generating, by the messaging management service, a message (127a-c) based on the message content type identifier, transmitting, by the messaging management service, the message (127a-c) and the account information for the user to the messaging service; receiving, by the messaging management service, new messaging service provisioning information for a new messaging service, wherein the new messaging service provisioning information includes: information that associates message content type identifiers to message templates that are formatted for the messaging service, and instructions for electronically communicating messages to the new messaging service; transmitting, by the messaging management service and to one or more message initiators, a notification indicating that messages may now be transmitted through the new messaging service; and receiving, by the messaging management service and from one or more of the message initiators, updated message recipient information that includes, for each of one or more of the multiple message recipients: updated preference data identifying the new messaging service, and account information for the new messaging service and the user. generating, by the messaging management service, a message (127a-c) based on the message content type identifier, transmitting, by the messaging management service, the message (127a-c) and the account information for the user to the messaging service; receiving, by the messaging management service, new messaging service provisioning information for a new messaging service, wherein the new messaging service provisioning information includes: information that associates message content type identifiers to message templates that are formatted for the messaging service, and instructions for electronically communicating messages to the new messaging service; information that associates message content type identifiers to message templates that are formatted for the messaging service, and instructions for electronically communicating messages to the new messaging service; transmitting, by the messaging management service and to one or more message initiators, a notification indicating that messages may now be transmitted through the new messaging service; and receiving, by the messaging management service and from one or more of the message initiators, updated message recipient information that includes, for each of one or more of the multiple message recipients: updated preference data identifying the new messaging service, and account information for the new messaging service and the user.