How to execute a git project with different input data?
Apparently the program expects a JSON file (probably) like this:

[
    {
    "id": ".......",
    "mailing_list_url": "......",
    "type_of_recipient": "......",
    "email_address": ".......",
    "message_body": "......",
    "is_response_of": "......"
    },
    {
    "id": ".......",
    "mailing_list_url": "......",
    "type_of_recipient": "......",
    "email_address": ".......",
    "message_body": "......",
    "is_response_of": "......"
    },

    ...

    {
    "id": ".......",
    "mailing_list_url": "......",
    "type_of_recipient": "......",
    "email_address": ".......",
    "message_body": "......",
    "is_response_of": "......"
    }
]


So if your data can be somehow converted to this that would be ideal, I guess. Otherwise you might have to play with the code.

Alternatively you could contact the authors by opening an issue.