Hello, Try encorporating DomainKeys and applying for their feedback loop. http://help.yahoo.com/l/us/yahoo/mail/postmaster/forms_index.html I still have the same problem. Do you have any users who forward their email to their free @yahoo.com addresses from your server? Let me know if you get in touch with anyone :) -Ray ________________________________________ From: owner-nanog@merit.edu [owner-nanog@merit.edu] On Behalf Of Justin Wilson [jwilson@corp.nac.net] Sent: Wednesday, February 27, 2008 10:01 AM To: nanog@merit.edu Subject: RE: Yahoo! Mail/Sys Admin Hello Everyone, It's been a while since I posted on this topic, and unfortunately I'm still having trouble with Yahoo deferrals. The links that were provided in this post worked, but after the forms were received by what I *think* is a human I still got a canned reply. I've tried replying with specific details about our problem, but is either answered with another generic reply or not at all. We are running Imall, and each domain has it's own IP address. Queue Timer and Tries before returning to sender are set to 30 minutes / 5 attempts. According to yahoo they do want you to attempt to resend if you get a 421 error. SPF is also set on a per-domain basis. I'm not sure what else to try. Does anyone have a better understanding of how Yahoo greylisting works? Thanks in advance! Justin Wilson