Russia-linked hackers tried at least five times to pry into Hillary Rodham Clinton’s private email account while she was secretary of state, emails released Wednesday show. It is unclear if she clicked on any attachment and exposed her account.

Clinton received the infected emails, disguised as speeding tickets, over four hours early on the morning of Aug. 3, 2011. The emails instructed recipients to print the attached tickets, which would have allowed hackers to take control of their computers.

Security researchers who analyzed the malicious software in September 2011 said that infected computers would transmit information from victims to at least three server computers overseas, including one in Russia. That doesn’t necessarily mean Russian intelligence or citizens were responsible.

Clinton has said repeatedly that the unusual homebrew server she used was secure.