Here’s what I got in reply. I only changed the gmail address and my domain:
This message was created automatically by mail delivery software.
A message that you sent could not be delivered to one or more of its
recipients. This is a permanent error. The following address(es) failed:
mygmailaddress@gmail.com
host gmail-smtp-in.l.google.com [142.250.110.26]
SMTP error from remote mail server after pipelined end of data:
550-5.7.26 This mail has been blocked because the sender is unauthenticated.
550-5.7.26 Gmail requires all senders to authenticate with either SPF or DKIM.
550-5.7.26
550-5.7.26 Authentication results:
550-5.7.26 DKIM = did not pass
550-5.7.26 SPF [myowndomain.de] with ip: [134.119.228.100] = did not pass
550-5.7.26
550-5.7.26 For instructions on setting up authentication, go to
550 5.7.26 https://support.google.com/mail/answer/81126#authentication 9-20020a05600c028900b0040b385ab364si6932246wmk.182 - gsmtp
Reporting-MTA: dns; smtprelay07.ispgateway.de
Action: failed
Final-Recipient: rfc822;mygmailaddress@gmail.com
Status: 5.0.0
Remote-MTA: dns; gmail-smtp-in.l.google.com
Diagnostic-Code: smtp; 550-5.7.26 This mail has been blocked because the sender is unauthenticated.
550-5.7.26 Gmail requires all senders to authenticate with either SPF or DKIM.
550-5.7.26
550-5.7.26 Authentication results:
550-5.7.26 DKIM = did not pass
550-5.7.26 SPF [myowndomain.de] with ip: [134.119.228.100] = did not pass
550-5.7.26
550-5.7.26 For instructions on setting up authentication, go to
550 5.7.26 https://support.google.com/mail/answer/81126#authentication 9-20020a05600c028900b0040b385ab364si6932246wmk.182 - gsmtp
Return-path: <max@myowndomain.de>
Received: from i6dfa39c6.versanet.de ([109.250.57.198] helo=[127.0.0.1])
by smtprelay07.ispgateway.de with esmtpsa (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
(Exim 4.96.1)
(envelope-from <max@myowndomain.de>)
id 1rDIG4-00009O-0P
for mygmailaddress@gmail.com;
Wed, 13 Dec 2023 06:58:12 +0100
Date: Wed, 13 Dec 2023 06:58:12 +0100
From: Max Wa <max@myowndomain.de>
To: mygmailaddress@gmail.com
Subject: neuer test
User-Agent: K-9 Mail for Android
Message-ID: <1736155A-8EFC-403A-8EFC-79C5D5087CA1@myowndomain.de>
MIME-Version: 1.0
Content-Type: multipart/alternative;
boundary=----MSKVQHHX3008I3GDWGJ42S1ZYE6PFI
Content-Transfer-Encoding: 7bit
X-Df-Sender: bWF4QG5lZ2dpc2NoLW5hZ2dpc2NoLmRl
I also compared the settings from Thunderbird and K9 closely and they all look the same.
When I sent from Thunderbird and have a look at the raw mail headers, it shows this:
Authentication-Results: mx.google.com;
spf=neutral (google.com: 134.119.228.104 is neither permitted nor denied by best guess record for domain of max@myowndomain.de) smtp.mailfrom=max@myowndomain.de
I’m puzzled. I just saw that from my phone, I sent to mygmailaddress@gmail.com while on TB, I sent to mygmailaddress@gmail.com. When I use @googlemail.com, it also works on K9. It doesn’t look like a K9 issue at all, but I’d be very pleased if you knew what’s happening here.