Q> Does Yahoo! use "greylisting" to reject messages? A> No. The most commonly understood form of "greylisting" is where an SMTP server will reject every message the first time it is attempted, and then accept it if the sending server retries later. The theory is that spammers won't retry messages, while legitimate senders will. Yahoo! does not utilize this method. http://help.yahoo.com/l/us/yahoo/mail/postmaster/postmaster-05.html -----Original Message----- From: owner-nanog@merit.edu [mailto:owner-nanog@merit.edu] On Behalf Of Mike Lewinski Sent: Thursday, April 10, 2008 1:10 PM To: nanog@nanog.org Subject: Re: Problems sending mail to yahoo? Barry Shein wrote:
Is it just us or are there general problems with sending email to yahoo in the past few weeks? Our queues to them are backed up though they drain slowly.
I know that Yahoo does greylisting, and we often have a large queue backup as a result of mailing lists with a lot of @yahoo.com addresses. As long as you keep retrying I find that they do eventually get through. Between greylisting and sender callback verification, it seems that overall email delivery is increasing in latency and decreasing in reliability.