When people choose what messages to send to others, they often consider how others will interpret the messages. In many environments, particularly in politics, people are motivated to hold particular beliefs and distort how they process information in directions that favor their motivated beliefs. This paper uses two experiments to study how message senders are affected by receivers' motivated beliefs. Experiment 1, conducted using an online sample of social media users, analyzes the effect of incentivizing senders to be perceived as truthful. These incentives cause senders to send less truthful messages. When incentivized, senders send more false information when it aligns with receivers' politically-motivated beliefs, controlling for receivers' current beliefs. However, receivers do not anticipate the adverse effects of senders' incentives. Experiment 2 further isolates the role that information processing plays by analyzing an environment in which receivers assess the truthfulness of messages from a computer and senders choose one of the computer's messages to determine their earnings. Senders predict that receivers distort information processing in the direction of their politics, demand information about receivers' political preferences, and condition on the receivers' politics to strategically choose less truthful computer messages.