Email sending broken after updating to 8.2.x (due to IPv6 issues)

[avatar1024]

@joseph said in Email sending broken after updating to 8.2.x (due to IPv6 issues):

Do you use netplan? If so, I could chek /etc/netplan/50-cloud-init.yaml . Does it have some statically assigned ipv6 block?

I was not aware I did use netplan (I don;t even really know what it is), but yes there is this config file and it seems to contain static IPs, see:

network:
  version: 2
  ethernets:
    eth0:
      match:
        macaddress: "xx:xx:xx:xx:xx:xx"
      addresses:
      - "152.xx.xx.43/22"
      - "2a03:4000:xx:xx:xxxx:xxxx:xxxx:6007/64"
      nameservers:
        addresses:
        - 46.38.225.230
        - 46.38.252.230
        - 2a03:4000:0:1::e1e6
      routes:
      - to: "default"
        via: "152.xx.xx.1"
      - on-link: true
        to: "default"
        via: "fe80::1"

If you tell me how i should modify the file then I'll try it out.

Thanks a lot for your help.

[joseph]

@avatar1024 said in Email sending broken after updating to 8.2.x (due to IPv6 issues):

  - "2a03:4000:xx:xx:xxxx:xxxx:xxxx:6007/64"

yup, this is the culprit. The IPv6 address is statically assigned here. You have to put a # in front of the line to comment it out and reboot the machine.

[avatar1024]

@joseph said in Email sending broken after updating to 8.2.x (due to IPv6 issues):

yup, this is the culprit. The IPv6 address is statically assigned here. You have to put a # in front of the line to comment it out and reboot the machine.

THANK YOU! That worked.

Seems like netplan is here by default since Ubuntu 18: https://pscl4rke.wordpress.com/2019/10/01/disabling-ipv6-on-ubuntu-18-04-the-netplan-version/

[joseph]

@avatar1024 I found this https://github.com/canonical/netplan/blob/main/doc/netplan-tutorial.md#editing-netplan-yaml-files-to-disable-ipv6 . Can't figure where this page is "published" . The yaml ref is at https://netplan.readthedocs.io/en/latest/netplan-yaml/

[potemkin_ai]

Just for the reference: netplan try is usually a better way, as it might save from end up getting locked out from the server. I also usually run a background cron task, that removes those temporary files from /etc/netplan, when messing with the network.

[privsec]

Ok, its not working again (or maybe it never did.

These are my screens

From my understadning, it is set up correctly.

[jdaviescoates]

@privsec said in Email sending broken after updating to 8.2.x (due to IPv6 issues):

its not working again

What exactly isn't working?

Have you set up the ipv6 reverse dns/ PTR /rDNS record too?

[avatar1024]

@jdaviescoates said in Email sending broken after updating to 8.2.x (due to IPv6 issues):

What exactly isn't working?

I imagine they are getting bounce to Gmail.

@jdaviescoates said in Email sending broken after updating to 8.2.x (due to IPv6 issues):

Have you set up the ipv6 reverse dns/ PTR /rDNS record too?

Looks like they have looking at screenshot 2....but possibly badly. I think it should say my.businessdoctorut.com

Though for me, after setting it all up properly I kept getting issues and random bounces with the same error message. Only completely disabling IPv6 from the network interface works (and even that turned out to be a struggle )

[privsec]

@avatar1024 My mail server location is

I do keep getting bounced emails from Gmail.

[potemkin_ai]

Just in case - I've just found that IPv6 might be enabled at the NetPlan level, despite all of the sysctl and other configs.

To disable - add to the appropriate yaml file in /etc/netplan - link-local: [ ipv4 ] - on the same level as dhcp instruction. Run netplan try and netplan apply if you are lucky.

That seems to disable IPv6 on Linux.

<rant> Linux start looking more and more like Windows </rant>

[avatar1024]

@potemkin_ai said in Email sending broken after updating to 8.2.x (due to IPv6 issues):

I've just found that IPv6 might be enabled at the NetPlan level

Yep this has been discussed above in this thread...from post #52 onward. The solution provided by @joseph worked on my end. I had originally tried something along the line you mentioned (adding link-local: [ ipv4 ] to the yaml file but that didn't work...although I might have done it wrong).

[avatar1024]

@privsec said in Email sending broken after updating to 8.2.x (due to IPv6 issues):

I do keep getting bounced emails from Gmail.

In that case I would just disable IPv6 altogether from your server network interface. That's the only only thing that worked for me.