The email dump will occur around 9:00 pm (0100 GMT Wednesday) on the State Department's Freedom of Information Act website, officials said.
Clinton's electronic correspondence has been the focus of controversy since her admission in March that she had used a private account for all her email correspondence while secretary of state between 2009 and 2013.
Republican rivals contend that Clinton, frontrunner for the Democratic presidential nomination in 2016, used the private account in order to keep it out of the public record.
But she has argued that as of late 2014 she had sent 55,000 printed pages from roughly 30,000 emails to officials who will archive the data and make it available to the public, as is required by law.
The remainder of the messages were deemed personal by Clinton and were deleted from her private server, she and her lawyers have said.
The State Department announced it intended to make the entirety of the archive public after purging it of classified or confidential information.
Clinton has backed the move, vowing transparency in the process after stressing she chose to use a private account for reasons of practicality and not obfuscation.
In May, a judge ordered the process accelerated.
The State Department's latest release would bring the amount of published emails to seven percent of the total, as required by the judge, State Department spokesman John Kirby said.
Half of the emails should be released by October 31, and the entirety of the archive screened and released by January 20, 2016.
The project is daunting, because officials will need to carefully review each document and redact sensitive data as necessary.
Speaking of the "enormity of the task," Kirby stressed that administration officials were "working right up to the deadline."
"There's been nothing but nearly non-stop work on this since the last tranche was released," he said, referring to nearly 300 Libya-related emails put out in late May.
Republican fodder
Republicans have seized on the email controversy in pressing their case that President Barack Obama's administration was unprepared for the 2012 attacks in Benghazi, Libya that killed four Americans, including the US ambassador.
Administrative and congressional investigations have highlighted security vulnerabilities at the US mission in Libya while Clinton was secretary of state.
Republicans, insisting that the Obama administration sought to conceal the terrorist nature of the attack, have created a special Benghazi committee in the House of Representatives.
The panel has been criticized by Clinton allies as a political tool to trip up the candidate on her White House quest.
Fueling Republican suspicions, the State Department acknowledged that 15 messages sent or received by Clinton and gathered independently by the agency were not included in the tranche delivered by her team.
source: www.abs-cbnnews.com
