The phrase "reach of one's message" refers to the extent or limit of how far a message can be spread, delivered or disseminated to an audience. Full definition
Your increase in sales and the broader reach of your message will be worth it! (magnoliamedianetwork.com)
They are trading on the perceived or potential reach of their message without quantifying that it's 2017, and that the mobile phone owns consumer attention, and everything is harder in marketing than it's ever been. (garyvaynerchuk.com)
Two communications experts have recently been engaged to work with OIPC to ensure the consistency and reach of messages about the new arrangements and SRAs in particular. (humanrights.gov.au)