[Koha] Email Delivery Notice Problem in Koha: Item due reminder and Advance notice Only

[Dr. Sambhunath Sahoo]

Hello,
I am currently using the *Koha 21.05 version* with MariaDB. For the last
two months, some (not all) of my users are not able to receive *only Item
due reminder and Advance notice email*. I am using Postfix MTA. Users are
getting other email notifications like checkout, checkin, membership
notifications, etc. Please suggest to me the possible solutions, if any.

*One of the failed issues is attached below for your reference.*
As per the message below, it seems to be a firewall Issue. But my IT team
told me it is not a firewall Issue.

* Delivery Failure Notification Message:*
From: <(unknown sender)>
Date: Wed, 14 Dec, 2022, 7:45 am
Subject: Delivery Failure Notification
To: <infolibrary at xxx.xx.in>

Sophos XG Firewall was unable to send the following mail:

----------------------
From: <infolibrary at xxx.xx.in>
MessageID: <16709841111.BB6A.31044 at koha.xxx.yy.in>
Sent on: 2022-12-14 07:37:53

Mail delivery to following recipients failed:

00pp009 at xxx.xx.in - Internal Server Error

Received: from localhost.localdomain (localhost [IPv6:::1])
        by  koha.xxx.yy.in (Postfix) with ESMTP id 55ED91A40C45
        for <00pp00 at xxx.xx.in>; Wed, 14 Dec 2022 07:45:11 +0530 (IST)
Date: Wed, 14 Dec 2022 07:45:11 +0530
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: quoted-printable
Subject: Advance Notice of Book(s) Due
From:  infolibrary at xxx.xx.in
To:  00pp00 at xxx.xx.in
Reply-To:  infolibrary at xxx.xx.in>
X-Mailer: Koha
Message-ID: <16709841111.BB6A.31044@ koha.xxx.yy.in>

Dear Mr. Raj Kumar,

The following book(s) will be due soon:

Title: The=20
Author: Guillebeau, Chris=20
Accession No.: 71119
Due Date : 16/12/2022 23:59

---
Thank you



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Regards,
Dr. Sambhunath Sahoo / डॉ सम्भुनाथ साहु
Assistant Librarian / सहायक पुस्तकालयाध्यक्ष,
Central Library / केन्द्रीय पुस्तकालय,
4th Floor, Administrative Building / चौथा मंजिल, प्रशासनिक भवन
Indian Institute of Technology Bhubaneswar / भारतीय प्रौद्योगिकी संस्थान
भुवनेश्वर
Argul, Khurda, Odisha /  आरगुल, खुर्दा, ओड़िशा,
752050 (India)
*ORCID ID:* 0000-0001-9162-879X
*Researcher ID:* K-4446-2018
*Scopus ID:* 57222542160
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