Yahoo Error: 421 4.7.0 (delivery delays)
Question asked by Christopher Delk - 10/15/2019 at 11:58 AM
Getting delays for Yahoo email deliveries:

Error: 421 4.7.0 [TSS04] Messages from ***.***.***.*** temporarily deferred due to user complaints -; see https://help.yahoo.com/kb/postmaster/SLN3434.html 

The Yahoo help link is vague and their bulk sender's form is basically an automated reply.  One site mentioned Yahoo using Spamhaus RBL, but I am not finding my server listed with them.

Wondering if anyone else had the same issue and has a solution.


4 Replies

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Employee Replied
Employee Post Marked As Answer

You may want to review this knowledge base article for further information on this issue:

Christopher Delk Replied

Thanks for the information.  Items 1 - 3 from the knowledge base are in place:

  1. Verify that a reverse DNS record is in place for all IPs that SmarterMail uses for outbound SMTP connections.
  2. Verify that an SPF record is in place for all hosted domains.
  3. Verify that DomainKeys/DKIM signing is enabled for your domains. (Versions 15.x and later no longer support DomainKey signing as that method for mail signing has become obsolete.)
  4. Use an outbound gateway with SpamAssassin and outbound filtering.

Is there a knowledge base for setting up outbound gateway with SpamAssassin and outbound filtering?  I saw this one, but it did not mention SpamAssassin:

Patrick Mattson Replied
I am having the exact same problem. I have changed my outgoing IP to IPs I have never used for outgoing email and Yahoo is bouncing them. Each new IP is giving me this error.

Also each domain has a DKIM and SPF record.

The problem is they are saying the IP is blocked due to complaints, but I have never used the IP as an outgoing IP. I have had these IPs for many years.

One thing I have noticed I changed the outgoing SMTP IP and my error logs are showing my primary NIC IP.
Linda Pagillo Replied
Patrick, I think your logs are showing your primary NIC because you may have your domains set to use it instead of using the domain's IP in SM. Instructions on how to check that in SM 15x, 16x, and 17x are here: http://know.mailsbestfriend.com/domains_in_smartermail_are_not_using_the_ip_assigned_to_them-1251571527.shtml

I hope this helps. Thanks!
Linda Pagillo Mail's Best Friend Email: linda.pagillo@mailsbestfriend.com Web: www.mailsbestfriend.com Authorized SmarterTools Reseller Authorized Message Sniffer Reseller

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