Response 421 for all emails to @gnu.org

Response 421 for all emails to @gnu.org

Hi,

for the past days almost all of my emails to any email address ending with @gnu.org are delayed, and some of them bounce.  At least one other Zoho user has the same problem (unlike me the user does not use domain hosting).

I contacted sysadmin@gnu.org and they told me that there is no problem on their end.  Here's an excerpt from their reply to me:


I'm seeing an occasional error from zoho for example:

2017-10-23 12:28:36 [25674] unexpected disconnection while reading SMTP command from sender-co9.zoho.com (sender1.zohomail.com) [135.84.80.240]:31020 I=[208.118.235.92]:25

Most mail going through for zoho.com is without any error.

Today we are seeing an error delivering mail to zoho.com:

SMTP error from remote mail server after RCPT TO:< REDACTED@zoho.com>: host smtpin.zoho.com [204.141.32.120]: 452 4.3.1 Temporary System Error
SMTP error from remote mail server after RCPT TO:< REDACTED@zoho.com>: host smtpin2.zoho.com [204.141.33.54]: 452 4.3.1 Temporary System Error

Here is an example of an email that was "returned to sender":

  1. Delivered-To: rekado@elephly.net
  2. Received: from mail.zoho.com by mx.zohomail.com
  3.     with SMTP id 1509019108562694.3318916481596; Thu, 26 Oct 2017 04:58:28 -0700 (PDT)
  4. Date: Thu, 26 Oct 2017 04:58:28 -0700
  5. From: mailer-daemon@mail.zoho.com
  6. To: rekado@elephly.net
  7. Message-Id: <15f588c44a5.ea84feb2-1109061582.-5184981302592202354@zohomail.com>
  8. In-Reply-To: <20171022120436.3688-1-rekado@elephly.net>
  9. References: <20171022120436.3688-1-rekado@elephly.net>
  10. Subject: Undelivered Mail Returned to Sender
  11. MIME-Version: 1.0
  12. Content-Type: multipart/mixed;
  13.     boundary="----=_Part_2100_1949923284.1509019108517"
  14. User-Agent: Zoho Mail
  15. X-Mailer: Zoho Mail
  16. X-ZohoMail: Z_26063301 SPT_1 Z_26062608 SPT_0
  17. ------=_Part_2100_1949923284.1509019108517
  18. Content-Type: text/plain; charset="UTF-8"
  19. Content-Transfer-Encoding: 7bit
  20. This message was created automatically by mail delivery software.
  21.  A message that you sent could not be delivered to one or more of its recipients. This is a permanent error.
  22. guix-patches@gnu.org, ERROR_CODE :421, ERROR_CODE :Host not reachable.
  23.  Received:from localhost (port-92-200-48-141.dynamic.qsc.de [92.200.48.141]) by mx.zohomail.com
  24.     with SMTPS id 1508673881501804.2995352416266; Sun, 22 Oct 2017 05:04:41 -0700 (PDT)
  25.  Message-ID:<20171022120436.3688-1-rekado@elephly.net>
  26.  Date:Sun, 22 Oct 2017 14:04:36 +0200
  27.  From:Ricardo Wurmus <rekado@elephly.net>
  28.  To:guix-patches@gnu.org
  29.  Cc:Ricardo Wurmus <rekado@elephly.net>
  30.  Subject:[PATCH] gnu: Add r-tgconfig.
  31. ------=_Part_2100_1949923284.1509019108517--

Here's an example of a delayed email:

  1. Delivered-To: rekado@elephly.net
  2. Received: from mail.zoho.com by mx.zohomail.com
  3.     with SMTP id 1509017678360762.7390955770818; Thu, 26 Oct 2017 04:34:38 -0700 (PDT)
  4. Date: Thu, 26 Oct 2017 04:34:38 -0700
  5. From: mailer-daemon@mail.zoho.com
  6. To: rekado@elephly.net
  7. Message-Id: <15f587671fd.b4f17da0473446118.-8049702226797712762@zohomail.com>
  8. In-Reply-To: <87inf2mbgq.fsf@elephly.net>
  9. References: <87inf2mbgq.fsf@elephly.net>
  10. Subject: Mail Delivery Status Notification (Delay)
  11. MIME-Version: 1.0
  12. Content-Type: multipart/mixed;
  13.     boundary="----=_Part_3002_398224763.1509017678333"
  14. User-Agent: Zoho Mail
  15. X-Mailer: Zoho Mail
  16. X-ZohoMail: Z_26063301 SPT_1 Z_26062608 SPT_0
  17. ------=_Part_3002_398224763.1509017678333
  18. Content-Type: text/plain; charset="UTF-8"
  19. Content-Transfer-Encoding: 7bit
  20. This message was created automatically by mail delivery system.
  21. THIS IS A WARNING MESSAGE ONLY.
  22. YOU DO NOT NEED TO RESEND YOUR MESSAGE.
  23. The original message was received at Thu, 26 Oct 2017 04:34:38 -0700
  24.  from rekado@elephly.net [rekado@elephly.net]
  25.     ----- The following addresses had fatal errors -----   
  26.    [Status: Error, Address: <guix-devel@gnu.org>, ResponseCode 421, Host not reachable.]
  27. Message will be retried for 4 more day(s)
  28.     ----- Transcript of session follows -----   
  29.  Received:from localhost (141.80.247.119 [141.80.247.119]) by mx.zohomail.com
  30.     with SMTPS id 1509014904965411.5159563818362; Thu, 26 Oct 2017 03:48:24 -0700 (PDT)
  31.  Message-ID:<87inf2mbgq.fsf@elephly.net>
  32.  Date:Thu, 26 Oct 2017 12:48:21 +0200
  33.  From:Ricardo Wurmus <rekado@elephly.net>
  34.  User-Agent:mu4e 0.9.18; emacs 25.3.1
  35.  To:REDACTED <REDACTED>
  36.  Cc:guix-devel <guix-devel@gnu.org>
  37.  Subject:Re: Tiny Guix (and containers)
  38.  Content-Type:text/plain; charset=utf-8
  39. ------=_Part_3002_398224763.1509017678333--

Best,
Ricardo