@proceedings{18251,
  author = {Alfred Arouna and Rick Fontein and Bernd Meijerink and Ioana Livadariu and Mattijs Jonker},
  title = {On the Role of Forward-Confirmed reverse DNS in E-mail Authentication},
  abstract = {Forward-confirmed reverse DNS (FCrDNS) (also known as prev), considered as client authenticity validation, is an early anti-spam effort to thwart spammers. Over time, anti-forgery techniques evolved with the advent of standards such as the Sender Policy Framework (SPF). SPF includes a ptr mechanism that encompasses an FCrDNS check. In this paper, we characterize the deployment of FCrDNS on prospective senders in practice, study to which extent iprev and SPF ptr checks are performed by large email providers on the receiving side, and how (non)compliance with FCrDNS affects email delivery. Our results show that two-thirds of the prospective senders with PTR record are FCrDNS-configured and that not all large providers strictly require iprev authentication. Our email campaigns show that large email providers exhibit different treatments of the SPF ptr mechanism, possibly because the SPF standard lacks clarity.},
  year = {2025},
  journal = {Network Traffic Measurement and Analysis Conference},
  publisher = {IFIP},
  isbn = {978-3-903176-74-4  {\textcopyright} 2025 European Union},
}