Building on from Juanita’s point of view, for me, this is far less a question of cost-effectiveness of channel and tailoring of message to ensure relevant.
If you are wanting to connect (which after all, is what marcomms is), then what is the VALUE you’re bringing to the table? What is your value prop? Is THIS relevant? Don’t annoy people with irrelevant offers let alone irrelevant comms. Innovate or refine your value prop to meet the NEEDS of your target audience. Get this right first and then, and only then, go out at communicate.