On Jul 31, 2010, at 11:22 AM, Hector Santos wrote:
> > J.D. Falk wrote: > >> It's not the wikipedia definition of greylisting, but they do use 4xx >> replies to control the flow of inbound mail. > > Ok, now I am starting to see 45x "grey listings", here is snap shot of a mail > queue: <snip> > There are multiple retries spread across different machines. > > Do you think they need the same exact IP or they support a class C > machine distribution? Yahoo isn't greylisting. http://blog.wordtothewise.com/2007/11/greylisting-that-which-yahoo-does-not-do/ "Yahoo is not keeping track of the mail it rejects and is not reliably allowing email through on the second attempt. There are a couple reasons why Yahoo is deferring mail. • Shedding load in a generic and non-specific way. • Shedding load by temporarily refusing mail from specific IPs. In the first case, the shedding of load means nothing more than Yahoo is shedding load. There is not really anything the sender can do to compensate for this, nor is there any thing the sender is doing (except possibly send mail to Yahoo at the same time as the rest of the world) to precipitate the blocking." laura -- Laura Atkins Word to the Wise "The Deliverability Experts!" Direct: 650 678-3454 Fax: 650 249-1909 AIM: wttwlaura YIM: wttw_laura Delivery blog: <http://blog.wordtothewise.com/>
