FiveThirtyEight concludes Clinton’s leaked emails had some impact on the 2016 presidential election, but can’t say how much. How Much Did WikiLeaks Hurt Hillary Clinton?
Had leaked emails been less boring and non-consequential, “smoking gun” sort of emails, their impact could have been substantial.
The lesson being the impact of campaign/candidate/party emails is impossible to judge until they have been leaked. Even then the impact may be uncertain.
“Leaked emails” presumes someone has leaked the emails, which in light of the 2016 presidential election, is a near certainty for the 2018 congressional mid-term elections.
Should you find yourself in possession of leaked emails, you may want a way to share them with others. My preference for public posting without edits or deletions, but not everyone shares my confidence in the public.
One way to share files securely and anonymously with specific people is OnionShare.
From the wiki page:
What is OnionShare?
OnionShare lets you securely and anonymously share files of any size. It works by starting a web server, making it accessible as a Tor onion service, and generating an unguessable URL to access and download the files. It doesn’t require setting up a server on the internet somewhere or using a third party filesharing service. You host the file on your own computer and use a Tor onion service to make it temporarily accessible over the internet. The other user just needs to use Tor Browser to download the file from you.
How to Use
http://asxmi4q6i7pajg2b.onion/egg-cain. This is the secret URL that can be used to download the file you’re sharing.Send this URL to the person you’re sending the files to. If the files you’re sending aren’t secret, you can use normal means of sending the URL, like by emailing it, or sending it in a Facebook or Twitter private message. If you’re sending secret files then it’s important to send this URL securely.
The person who is receiving the files doesn’t need OnionShare. All they need is to open the URL you send them in Tor Browser to be able to download the file.
(emphasis in original)
Download OnionShare 1.1. Versions are available for Windows, Mac OS X, with instructions for Ubuntu, Fedora and other flavors of Linux.
Caveat: If you are sending a secret URL to leaked emails or other leaked data, use ordinary mail, no return address, standard envelope from a package of them you discard, on the back of a blank counter deposit slip, with letters from a newspaper, taped in the correct order, sent to the intended recipient. (No licking, it leaves trace DNA.)
Those are the obvious security points about delivering a secret URL. Take that as a starting point.
PS: I would never contact the person chosen for sharing about shared emails. They can be verified separate and apart from you as the source. Every additional contact puts you in increased danger of becoming part of a public story. What they don’t know, they can’t tell.