A new study of consumers brings some surprising details about “dark” social network usage to light.

Thirty-two percent of consumers who share content with friends and acquaintances by digital means told Tpoll researchers they do it via email, SMS, and other peer-to-peer platforms, services known as “dark social” channels as they are not quite as easy to monitor as “light social” mediums like Facebook, Twitter, and Tumblr.

RadiumOne, the advertising platform responsible for releasing the Tpoll report, claims consumers underestimate their own usage of “dark” social channels; pointing to trends measured by their on PO.ST content-sharing widgets, they see “dark social’s” share of content sharing as being closer to sixty-nine percent, flipping Tpoll’s self-reported figure on its head and then some. 33Across’ own Tynt would seem to agree with those findings, as their work tracking copy-and-pasting of digital content found seventy percent of sharing performed via “dark social” channels.

RadiumOne’s report is careful to note “dark social”’s consequences for brands and marketers. “Sharing activity through email, instant messaging and forum posts, aka ‘dark social’, is three times larger than on Facebook, globally,” the report notes, going on to point out that “dark social” accounts for the “majority” of sharing in nineteen content categories important to advertisers including travel, finance, and technology.

As email, SMS, and similar mobile-friendly digital platforms are much harder to track and analyze than content shared on major social networks by virtue of their ad-hoc, decentralized nature, marketers will have to drill deeper than ever before to target advertisements to individual consumers as accurately as possible.