domain @nhs.net

We are having a sudden issue with our email that we appear to be unable to send emails to the domain @nhs.net

Emails to other emails are sending fine however no @nhs.net emails are not letting us send.

We have been able to until the last few days. They are receiving emails fine from other people. They are not in the blocked list, we have sent and received emails from them many times before.

We are getting the following bounce back email whenever we email:

This message was created automatically by mail delivery system.

THIS IS A WARNING MESSAGE ONLY.

YOU DO NOT NEED TO RESEND YOUR MESSAGE.

The original message was received at Thu, 19 Sep 2024 14:14:23 +0200
from

----- The following addresses had fatal errors -----

Message will be retried for 4 more day(s)

Reporting-MTA: dns; mx.zohomail.eu
Arrival-Date: Thu, 19 Sep 2024 12:29:14 +0100

Original-Recipient: rfc822;
Final-Recipient: rfc822;
Status: 421
Action: failed
Last-Attempt-Date: 19 Sep 2024 12:14:23 GMT
Diagnostic-Code: HostName not valid
Remote-MTA: dns; esg.nhs.net

Received:from mail.zoho.eu by mx.zoho.eu
with SMTP id 1726745354509239.10726822126628; Thu, 19 Sep 2024 13:29:14 +0200 (CEST)
Message-ID:<.>
Date:Thu, 19 Sep 2024 12:29:14 +0100
From:<
To:
Cc:
Subject:Falls Referral
Content-Type:multipart/mixed;
boundary="----=_Part_6994171_7472851.1726745354354"
User-Agent:Zoho Mail

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