Only in the most liberal sense of the phrase "DRM" (which IMO would be a useless definition as many platforms/apps have analogous intentional and unintentional barriers, but they're not called "DRM"), but not DRM as we know it. While the decision is on the sender's side, a crucial distinction is that the sender enjoys the same power as the recipient in the conversation - very similar to information sharing between friends IRL. Calling it "DRM" is just pedantic.