An integrated email security gateway and dual-layer frequency-domain watermarking framework for business transaction receipt authentication against generative AI manipulation. Journal of Soft Computing Exploration, [S. l.], v. 7, n. 3, p. 561–570, 2026. DOI: 10.52465/joscex.v7i3.77. Disponível em: https://joscex.shmpublisher.com/index.php/journal/article/view/77. Acesso em: 20 aug. 2026.