Email with synapse

[ginoo]

Submitting the headers you provided to that analysis tool, we have information that SPF and DKIM failed, and that DMARC is missing.

And the x.cloud domain isn't even registered, so it couldn't possibly have SPF, DKIM, and DMARC configured. Setting up these things in an internal DNS zone isn't enough, unless the destination email service is also internal. As a rule, you need to configure it in an external DNS zone, which requires having the domain registered.

I wrote it above, I changed the domain to avoid spam, if you look at the headers you will see that everything is ok.

[ginoo]

Anyway, thanks to both of you. I'll try tomorrow.

[rvk]

Seeing the number of a-records in the X-CNFS-Analysis header (which would mean multiple rules are hit) I guess it has more to do with content.

BTW. You can also send the mail to some spam tester to see what it makes of it.
For example https://www.mail-tester.com/
and https://unspam.email/
and https://www.mailgenius.com/
and https://www.experte.com/spam-checker
and https://mailchecker.net/
and many many more 

[rvk]

https://www.mail-tester.com/  gives me 10/10

Then it must be content related (as I said earlier, seeing those X-CNFS-Analysis a records).

For example spamassassin has lots of rules for content. If you have white text on white background. If you have double spaces. And thousands of other things.

The only one who can diagnose those headers is Cloudmark (I think the mail goes through Cloudmark Authority).

I haven't seen anyone else decrypting those headers.
(someone asked here: https://github.com/mgeeky/decode-spam-headers/issues/5)