Email delivery of certificates fails

[andremano]

Yesterday we issued nine certificates. The email delivery for all of them failed - I reproduce one of the messages below. Email domains include Yahoo, Gmail, Live and Outlook.

For now, we emailed the certificates individually, one by one, but for courses with larger attendances, it is really not ideal.

---

Delivery has failed to these recipients or groups:
certificate_recipient@yahoo.com
Your message wasn't delivered because the recipient's mailbox is quarantined. If the problem
continues, please contact your email admin.
The following organization rejected your message: mta6.am0.yahoodns.net.
Diagnostic information for administrators:
Generating server: kartoza.com
_certificate_recipient_@yahoo.com
mta6.am0.yahoodns.net
Remote Server returned '554 5.7.9 <mta6.am0.yahoodns.net #5.7.9 smtp; 554 5.7.9 Message not accepted for
policy reasons. See https://postmaster.yahooinc.com/error-codes>'
Original message headers:
Return-Path: <_course_convener_@utwente.nl>
Received: from 5229f28bbcc7 (unknown [10.42.189.83])
 by kartoza.com (Postfix) with ESMTPA id 8A9862DD5
 for <certificate_recipient@yahoo.com>; Thu, 19 May 2022 11:12:12 +0000 (UTC)
Content-Type: text/plain; charset="utf-8"
MIME-Version: 1.0
Content-Transfer-Encoding: 7bit
Subject: Certificate from IdeaMapSudan - A Training of Trainers course on
 spatial
 analysis and models of deprivation Course
From: <Course_convener@utwente.nl>
To: <certificate_recipient@yahoo.com>
Date: Thu, 19 May 2022 11:12:12 +0000
Message-ID: <165295873256.921.10688980296239735937@5229f28bbcc7> 

[dimasciput]

Hi @andremano , could you please test again? The email should be sent successfully, but for now it will go to the spam folder.

@timlinux we need a email server and email account, could you create one please?

[andremano]

Yes, it is working now. Some of the attendees got the link directly to the Inbox, while others to the Spam folder. But no emails were rejected.