Yahoo SMTP Server: Delivery Temporarily Suspended

Recently the outgoing messages to Yahoo from my Linux boxes are all deferred. The linux box hosts a website which contains a webform, which sends about 200 mails to 100 subscribed accounts, which is about 20K messages per day. About 13 accounts are Yahoo addresses. I use Postfix and below is the results from “mailq”.
7AE4531F83EE 1895 Fri Apr 5 22:08:17 apache@myhostname
(delivery temporarily suspended: lost connection with mta7.am0.yahoodns.net[66.196.118.35] while performing the HELO handshake)
xxxx@yahoo.com

 

Tried to telnet to port 25 of Yahoo’s SMTP server, and this is the message:
421 4.7.0 [TS02] Messages from xx.xx.xx.xxx temporarily deferred – 4.16.56.1; see http://postmaster.yahoo.com/errors/421-ts02.html
Connection closed by foreign host.
Contacted Yahoo using two online forms:

1. Yahoo! Mail Delivery Issues Form

2. Yahoo! Mail Bulk Sender Form

I submitted the form On Sunday, got reply from Yahoo for the second form on following Tuesday. Here is the response:

Thank you for contacting Yahoo! Mail.

The information you have sent us has been updated in our system. Feel free to test things out and let us know if you experience any problems, so we may assist you further to resolve your issue.

Your patience during this process is greatly appreciated.

Thank you again for contacting Yahoo! Mail.

Regards,

Yahoo! Customer Care

Checked the server, the mails are still deferred and total number of mails in the mailq is still rising.

So I followed up with Yahoo using the first form again, with the incident ID I got earlier. Got response within 3 hours:

Thank you for contacting Yahoo! Mail.

We have reviewed the IP information you have provided and made the appropriate changes in our database. As a result, the recent deferrals you have referenced in your report should now be resolved.

If you need further assistance or to see the latest information with regard to delivery to Yahoo! Mail, please visit:
Your patience during this process is greatly appreciated.

Thank you again for contacting Yahoo! Mail.

Regards,
Yahoo! Customer Care

After getting this mail, I checked the server and half of the queue has been cleared (about 3500 messages were sent).

 

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