Hillary Rodham Clinton was warned against revealing her private email practices at the State Department over hacking fears.

An aide to Clinton sent an email on a June 4, 2011 suggesting that the then-secretary of state and her staff not “telegraph” that some officials were using private email accounts on which they conducted government business, according to messages made public Wednesday.

The aide, chief of staff Cheryl Mills, suggested to Clinton and others that she had been the victim of an attempted hacking and wrote that she was “not sure we want to telegraph how much folks do or don’t do off state mail b/c it may encourage others who are out there.”

Clinton’s presidential campaign has faced months of questions and dozens of lawsuits because she used a private email server for some daily communications. Many experts contend her setup might have been insecure, and government inspectors general have found information that they say should have been classified among the emails. (The campaign disputes this.)

It was also learned Wednesday that hackers did indeed attempt to access Clinton’s account just two months later, sending a series of phony emails disguised as parking tickets and soliciting the recipient to click an attachment that would have transmitted information to overseas servers, including one in Russia, The Associated Press reported. It’s unclear if Clinton clicked the attachments.

The warning from Mills was prompted by an email from another State Department employee, Anne-Marie Slaughter, who wrote on June 3 “that State’s technology is so antiquated that NO ONE uses a State-issued laptop and even high officials routinely end up using their home email accounts to be able to get their work done quickly and effectively.” The subject line refers to an apparent hack of Gmail and the “woeful state of civilian technology.”

Before Mills’ warning, Clinton responded that Slaughter’s proposed remedy — going public about the issue with a statement or an op-ed from someone at the department — “makes good sense.”

In addition to Clinton’s two private email accounts, another key aide, Huma Abedin, used a personal account on the Clinton server. Slaughter, who now heads the New America think tank, also appeared to be using a private account, as her address was redacted by the State Department so as not to violate personal privacy, although it’s unclear if the address was on Clinton’s private domain, clintonemail.com. An AOL account of close Clinton ally and frequent correspondent Sidney Blumenthal would later be hacked, and his private memos to Clinton ended up on the Internet.

A State Department spokesman declined to comment on Wednesday’s revelations. A lawyer for Mills did not comment on the record. Representatives for New America and a Clinton campaign spokesman did not immediately respond to a request for comment.

The latest release of Clinton’s emails is part of the ongoing process by the State Department of making her correspondence public in response to requests under the Freedom of Information Act. Clinton was not alone in using a private email address while heading the department. Former Secretary of State Colin Powell has also said he used a private email address when he held the position from 2001 to 2005.