First of all thank you all for looking into this!
Let me explain the situation. We have a MIAB server (box.betanine.be) running on a DO droplet for many years. This instance is used mail and DNS server for multiple domains including (of course) betanine.be but also t3-platform.net.
t3-platform.net is a track&trace platform that we host from our own servers in a datacenter in Brussels. All services run on tens of LXD containers and all use box.betanine.be to send out mails.
This is a situation that exists for many years, and so far all mails came through normally. But since the upgrade to v0.52, they are all marked as spam, and I see these headers in the mails that were not there before:
Authentication-Results: box.betanine.be; dmarc=fail (p=quarantine dis=none) header.from=t3-platform.net
Authentication-Results: box.betanine.be; spf=fail smtp.mailfrom=noreply@t3-platform.net
Authentication-Results: box.betanine.be; dkim=none; dkim-atps=neutral
What I would like to know is where these headers suddenly come from, and of course how I can avoid them. I don’t think that adding all my containers to the SPF string is the solution.
I also used mxtoolbox.com to check and I don’t see anything wrong with the DNS configuration for the domains.
The mails that have these headers are sent via a Java client and the service is defined the following (an example as there are many of these):
<SMTP name=“mail” subject="[T3 GIS Server] - Report" to=“t3-error@beta9.be” from="noreply@t3-platform.net"
smtpHost=“box.betanine.be” smtpPort=“25” bufferSize=“100” smtpUsername=“error-reporting@betanine.be”
smtpPassword=“xxxxxx”>
<PatternLayout pattern="%d{yyyy-MM-dd HH:mm:ss} %p: %x - %m%n"/>
</SMTP>