They must be processing a increased TCP/SMTP connection load that is an order of magnitude larger then before this alledged new policy.
Add in DNS lookups, RBL lookups, manual block lookups, you get the point. Unfortunately, you are simply pissing off our end users and giving yourself a black eye in the community.
Also, the admin on a Yahoo Freecycle group posted today they saw over 500 address bouncing!It seems this issue is impacting Yahoo´s own services as well. Of course their mail servers are having capacity issues. If you block the first attempt at delivery of each message, most legit servers will try again, and again, and again.You may retry sending at a later time when you see this message.However please note that emails from the mail server(s) you are using may also have recently become deprioritized due to potential issues with its mailings.(They have a high incentive because work is on a first-come-first serve basis.
It´s tricker with clients to try and explain why our e-mails are delayed by many hours and are ending up in their junk mail folder.
Would Domain Keys actually help since the servers are rejecting upon connect?
(since the domain key looked up is based on selector in the message header, which doesn´t even get sent).
Yesterday I Googled for "451 Message temporarily deferred yahoo" and today, serveral of threads on Yahoo´s message boards have now been deleted.
They were mostly from concerned legitimate users who were wondering why their e-mail were being delayed by hours if not days.
There appears to have been an incident involving capacity issues within our delivery infrastructure.