All email to Google domains is marked as spam

Problem Description

Since switching my personal email over to Sympl, all outgoing emails to domains where Google hosts the email (e.g. gmail.com) are being marked as spam, which effectively means they’re silently deleted. I’ve already made sure the following are in place:

  • SPF: "v=spf1 mx ~all" in DNS (all outgoing mail goes via my MX)
  • DKIM: I’ve generated a key and all outgoing mail is being signed, plus I’ve published the DNS record.
  • DMARC: I’ve got a basic DMARC record which says don’t take any action (I’m planning to change this to p=reject once I know everything works).

If I view the full email headers in Gmail, I get PASS for SPF, DKIM and DMARC.

I’ve checked various blocklists and it doesn’t look like the IP addresses of the server are listed.

The hostname of the machine resolves to IPv4 and IPv6 addresses, and those addresses match the hostname on a reverse DNS lookup. The same hostname is used as my MX record and I’ve regenerated the TLS certificate so that it comes from LetsEncrypt instead of being self-signed, although I don’t think mail servers are particularly fussy about that.

I’ve run various online tests and the only thing my server gets told off for are:

  • Sender and hostname domains are not signed with DNSSEC.
  • DMARC policy is p=none.
  • TLS 1.1 is supported
  • DH-2048 key exchange is supported

I don’t know if this is a problem with Sympl or not, but is there anything else I can configure to try and get mail delivered to Google inboxes? Is there a way to disable outgoing mail on IPv6 for example, as I remember Google used to be laxer about checking mail delivered over IPv4?

The hostname is romana.vs.mythic-beasts.com and the domain for the email is xk7.net.

Environment

  • Sympl Version: 10.0
  • Sympl Testing Version? No
  • Debian Version: Buster
  • Hardware Type? Virtual
  • Hosted On? Mythic Beasts

I’m no expert, but have some experience I can share…

Have you tested your DKIM settings? This is a really good tool for that - https://www.appmaildev.com/en/dkim

Are you sending the email via gmail, or via your server?

My server is a brightbox machine and my SPF ended up being quite complex to sort out:
“v=spf1 +mx +a +a:ipv6.servername.gb1.brightbox.com include:_spf.google.com ~all”
Do you need anything extra on Mythic beasts to handle IPv6?
Also make sure your SPF record is in the right order. I seem to remember I had an ordering issue when I set it up.

I have tested my DKIM settings - they get PASS if I view the mail via Google and the mails are signed by xk7.net. I’ve tested with some other sites as well.

All my mail goes out via my server so my SPF record is correct, and worked on my previous server.

I shouldn’t need to do anything else on Sympl/Mythic - mail is delivered over IPv6 without any problems (e.g. to other providers) and the right AAAA + PTR records are in place.

Hi @pwaring, if you’re still having problems with this, drop Mythic Support a mail with some headers and we should be able to look into it in detail.

Thanks. Mail seems to be delivered to inboxes now, it looks like it takes Google a week or so to start ‘trusting’ a new mail server, though the fact that they don’t reject as part of the SMTP dialog makes it really difficult to tell.

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