Greetings, The Sender Policy Framework (SPF) is an easy way to check whether the sender is authorized to send emails – however, it may cause some security holes if it causes too many DNS lookups. Together with researchers from Virginia Tech and Max-Planck-Institut für Informatik, we would like to understand which challenges operators face when configuring the proper limit of DNS queries for SPF lookups and when deploying other email security protocols. Filling out the survey should take between 5 and 10 minutes; we would highly appreciate your participation. https://www.surveymonkey.com/r/D9M3ZHV Please note that we do NOT collect any personal information, thus the Institutional Review Board (IRB) at Virginia Tech determined the survey as Non-Human Subjects Research. We will aggregate and anonymize all responses during evaluation and share the results after evaluation. Please do not hesitate to drop me a mail if you have questions or comments. Also, please excuse us if you have received this email from different mailing lists. Thank you. Taejoong "Tijay" Chung, Assistant Professor Virginia Tech | Computer Science Knowledge Works II, RM 2228 2202 Kraft Drive, Blacksburg, VA 24060 (540) 231-0667| tijay@vt.edu