A method includes receiving a first request associated with a first user account and comprising content of a first message, and a second request associated with a second user account and comprising content of a second message, generating a first list of routing options for delivering the first message to a first plurality of destination endpoints, and a second list of routing options for delivering the second message to a second plurality of destination endpoints, determining a first optimal routing option for delivering the first message, determining, a second optimal routing option for delivering the second message, causing one or more versions of the first message to be transmitted to the first plurality of destination endpoints using the first optimal routing option, and causing one or more versions of the second message to be transmitted to the second plurality of destination endpoints using the second optimal routing option.