Problems sending mail to yahoo?

Frank Bulk frnkblk at
Thu Apr 10 18:48:52 UTC 2008

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.

-----Original Message-----
From: owner-nanog at [mailto:owner-nanog at] On Behalf Of Mike
Sent: Thursday, April 10, 2008 1:10 PM
To: nanog at
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 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

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