A messaging service is described which provides application agnostic and cross-platform messaging. Senders compile message content components and specify message preferences. The messaging service calculates a utility and cost of sending the message over different types of communication channel. A communication channel is selected using the cost and utility information and the message service formats the message content components for the particular communication channel. The message is then sent for example, as email, SMS, MMS or other suitable type depending on the selected channel. The utility is calculated using the sender message preferences, communication channel attributes, sending and recipient device attributes and preferably also, but not essentially, preferences of the recipient.