The whistleblowing organisation went ahead with publishing despite an orchestrated cyberattack on its servers, and an attempt by the government to block the website in Turkey.
The most recent email in the trove was sent on 6 July 2016, a week before the coup, dating back as far as 2010.
WikiLeaks said the release of 300,000 emails, with several thousand attached files, is just the first in the series and encompasses 762 mailboxes from "A" to "I".
Accompanying the leak, it said on its website: "It should be noted that emails associated with the domain are mostly used for dealing with the world, as opposed to the most sensitive internal matters."
True to its word, there is plenty of spam from Nigerians with fortunes to bequeath upon you, conspiracy theories and press releases.
In pictures: Turkey coup attempt
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But given there are 294,548, it may be a while yet until something more interesting in uncovered.
John Kerry: Turkey coup could threaten country's Nato membership
At least 50,000 people have been rounded up, sacked or suspended from their jobs following last week's attempted coup.
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