I am getting error from google postmaster (Unique Local Adress problem?)

kameit00

Hi,

I am getting errors from google.

This is the error message:
host gmail-smtp-in.l.google.com[2a00:1450:4013:c04::1a]
said: 550-5.7.25 [2a01:4f8:c2c:1b78::1] The IP address sending this message
does not 550-5.7.25 have a PTR record setup, or the corresponding forward
DNS entry does 550-5.7.25 not match the sending IP. As a policy, Gmail does
not accept 550-5.7.25 messages from IPs with missing PTR records. For more
information, go 550-5.7.25 to 550-5.7.25
https://support.google.com/a?p=sender-guidelines-ip 550-5.7.25 To learn
more about Gmail requirements for bulk senders, visit 550 5.7.25
https://support.google.com/a?p=sender-guidelines.
a640c23a62f3a-aaf6ada54bfsi546788666b.864 - gsmtp (in reply to end of DATA
command)

When I look inside the headers of Mails to another server (the mails to google don’t go through) I can see something strange.

Received: from mail.relax-pillow.de ([fd4d:6169:6c63:6f77::e])
by bdf013f9b8f3 with LMTP
id iMQBL6MSeGdCJAMA3OxuXQ

This is NOT my IPv6 Adress, it looks like a Unique Local Adress, that mailcow is using. But why?

I recently updated the server to ubuntu 24. Now I realize this.

pkernstock

kameit00 said: 550-5.7.25 [2a01:4f8:c2c:1b78::1] The IP address sending this message

I’d rather suspect this being your IPv6 address of your Hetzner VPS - as this IP range is owned by Hetzner, not Google. My best guess would be that you have IPv6 enabled, but IPv6 neither configured on your mail.relax-pillow.de FQDN nor the respective PTR.

Either disable IPv6 entirely (as per docs), or finish the IPv6 setup (configure AAAA record + PTR).

kameit00

Thanks for answering!

Would you mind to review my settings with me?
Yes, I am on a Hetzner VPS. IPv6 is enabled, and I thought it was configured correctly.

Here are some infos…

On the mailcow server:

hostname gives:

mail.relax-pillow.de

hostnamectl gives:

Static hostname: mail.relax-pillow.de Icon name: computer-vm Chassis: vm 🖴 Machine ID: 2196334bf1b844daa3a0eab1f3cac158 Boot ID: 5406d191931e42099d6c3c3ad8045bba Virtualization: kvm Operating System: Ubuntu 24.04.1 LTS Kernel: Linux 6.8.0-51-generic Architecture: x86-64 Hardware Vendor: Hetzner Hardware Model: vServer Firmware Version: 20171111 Firmware Date: Sat 2017-11-11 Firmware Age: 7y 1month 3w 2d

The content of /etc/hosts:

127.0.1.1 mail 127.0.0.1 localhost 116.203.124.138 mail.relax-pillow.de mail ::1 ip6-localhost ip6-loopback fe00::0 ip6-localnet ff00::0 ip6-mcastprefix ff02::1 ip6-allnodes ff02::2 ip6-allrouters ff02::3 ip6-allhosts 2a01:4f8:c2c:1b78::1 mail.relax-pillow.de mail

And these are my settings at Hetzner:

I can’t figure out what’s wrong… 🙁

Thanks again for your answer.

kameit00

I also found a glitch…
In my SPF Record (“v=spf1 a aaaa mx _all”) there was the ‘aaaa’ part - which seems to be invalid, since ‘a’ also covers the AAAA records.
I removed that now.

I did a test order on the shop to my GMail adress and the order went through to my Gmail account. Maybe after checking and editing the above, the configuration is now ok.

If anybody spots other errors or has reccomendations - I am happy to get those and learn from you.

pkernstock

Now the DNS is fine - the AAAA record is set:

$ dig mail.relax-pillow.de AAAA @1.1.1.1 +short
2a01:4f8:c2c:1b78::1

It wasn’t at the moment I replied the first time earlier. Maybe you haven’t given DNS enough time to propagate it’s DNS records across the globe.

kameit00

Could well be pkernstock!
And thanks for the command above - right, I could have checked it with Googles DNS 1.1.1.1! Another note in my journal for future problems.
Thanks for your helping hand mate!