I’ve looked at the sources of this paper, and it looks like the grams of CO2 per email are taken out of the ass, as it’s just a random value in „SAMRIDDHI Volume 15, Issue 1, 2023 Print ISSN: 2229-7111 Online ISSN: 2454-5767 Survey on Carbon Dioxide Emissions Through Email Conversion”
Stolen? It was forked as is allowed by the MIT license. With GPL as well there is no „you cannot fork” rule, you can do exactly the same thing. The author misunderstood that „you have to push the changes to upstream”, which is not in any of those licenses.