“ ‘[F]oldering.’ ”

It’s not in the dictionary, so what is this “foldering” of which former Trump campaign chairman Paul Manafort stands accused by a federal prosecutor?

Essentially, it’s a manner of communicating, theoretically undetected, via messages entered into an email application but left unsent. Other parties with access to the account’s user name and password are then free to retrieve and read the messages and respond as wished, again leaving their messages in draft mode.