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Newly-released Hillary Clinton emails show her concern about...email

Last Updated Jul 31, 2015 6:11 PM EDT

The State Department on Friday released 1,356 of Hillary Clinton's emails from her tenure as secretary of state, in its continued effort to comply with Freedom of Information Act requests.

The emails date back to 2009, Clinton's first year in the Obama administration. While most of the emails released Friday were of little significance, one casual email showed that Clinton may have had concerns about her electronic communications. Clinton sent an email to one of her top aides, Cheryl Mills, on Dec. 1, 2009 with the subject line "May I borrow."

In the email, the secretary of state asks to borrow the book "Send" by David Shipley. The book's full title happens to be "Send: Why People Email So Badly and How to Do It Better."

Another email from the U.S. ambassador to Iraq, Christopher Hill, betrays some frustration about his dealings with the Iraqis. In Nov. 2009, in response to an email from Clinton, who had congratulated him on his work on the Iraqi election, Hill responded, "...[W]ish I felt better about Iraqis as a result, but I truly remain worried about these people. They are truly a collective pain in the neck." Hill was ultimately unable to broker a deal on the formation of the Iraqi government before he left his post in 2010.

There are other emails that mention positive press coverage, and Clinton's appearance. One August 2009 email from Abedin advises Clinton, "Wear a dark color today Maybe the new dark green suit Or blue." Another from Abedin says that Barbra Streisand and James Brolin asked whether she and Bill Clinton were free for dinner in New York.

The latest release of emails comes amid continued questions about whether Clinton and her staff mishandled any classified or sensitive government information in her inbox. Clinton has come under fire for using a private email account and private server to conduct business, rather than an official State Department address.

State Department Spokesman Mark Toner said portions of 37 documents in Friday's release had been upgraded to "confidential." He also confirmed that this number is higher than in any of the past releases.

The State Department has now released three large batches of emails from Clinton's account, though it is still reviewing the vast majority of the more than 55,000 pages of emails that Clinton handed over to the department.

On Wednesday, a judge scolded the State Department for its slow release of Clinton's records. The next day Clinton insisted that she is personally releasing the emails in question in a "timely fashion."

"The vast majority of the emails that I have turned over and that are being turned over by others were already in the State Department system," she said.

Many of the emails released Friday were heavily redacted, and many related to personnel issues as Clinton built up her staff in the State Department.

CBS News' Alicia Amling and Brian Gottleib contributed to this report