During the 2017 campaign for French presidency, the campaign of Emmanuel Macron became the target of a disinformation campaign from a combination of Russian and American alt-right operatives. Starting in January 2017, the candidate's and his staff's email accounts were targeted by hackers. Shortly before the May 2017 final vote, a trove of hacked emails, supplemented with some forged documents, was leaked on social media, accompanied by the spreading of false rumors about Macron's financial dealings, infidelities, and sexual orientation. The rumors were broadcast by Russian state-owned outlets RT and Sputnik, while the leaks were amplified on Facebook and Twitter, primarily by English-speaking accounts. The goal was to suppress the turnout of Macron's supporters and maximize the electoral chances of far-right candidate Marine Le Pen.
The Macron campaign and the French government were well-prepared for the possibility of hacks. The campaign closely monitored their servers and reported all suspicious activity as it was happening. When the documents were leaked and the rumors started spreading, the campaign worked with social media platforms to tamp them down, and with journalists to expose disinformation early on. The candidate was forthcoming about the rumors during interviews, injecting humor into the situation. The final trove of documents was posted within 48 hours of the vote, during which time French laws do not allow political coverage in mass media. Government officials reminded journalists of this blackout, and they complied by not writing about the leak. As a result, the disinformation campaign had no tangible outcome on voter turnout or final vote; Macron won decisively.
The French media ecosystem is not hyper-partisan (unlike the US or UK). The average citizen reads multiple news sources and does not fully trust any of them. News consumption from online outlets or social media in 2017 was low relative to other Western nations.
French law has explicit limitations on election-related speech and political advertisement, with a complete blackout for 2 days before elections. Electoral campaign are short and have multiple rounds, reducing the chance of surprise outliers. Election laws are enforced by trusted, non-political governmental bodies.
The French government was warned about the possibility of info operations from earlier efforts in neighboring countries. It was clear that the info-op came from abroad (Russian and American alt-right sources), which made it easier to inoculate the public.