550-5.7.1 Our system has detected that this message does not meet IPv6 sending guidelines regarding PTR records and authentication

I think I finally got this issue fixed.


550-5.7.1 Our system has detected that this message does not meet IPv6 sending guidelines regarding PTR records and authentication. Please review 550-5.7.1

I first mentioned the problem with the IPv6 warning in this thread.  And then I mentioned it again here.  And I had thought it was just gmail being overly strict and had about given up and switched to Hotmail after this thread.  And hopefully this will be the last in the series.  The IPv6 issue was a bit complicated to fix with Cyberpanel.  Here are the steps:

  1.  IPv6 is not natively supported in Cyberpanel.  To add IPv6 support I followed these directions.
    1. I added webadmin console for cyberpanel following this guide
    2. I went into webadmin console and created 2 new IP address entries as described in the guide – one for general and one for SSL
    3. I copied most of the settings from the IPv4 listeners set-up natively by cyberpanel
    4. I added each of the domains I want to use for sending email and/or have an IPv6 address for the website – make sure you add the domains for both the regular AND the SSL listener you created.  At first I forget to add the domains for the SSL IPv6 listener and I got an unsafe website warning and then a 404 page not found message from the server
  2. Go to Cloudflare DNS settings and I added the following additional entries:

AAAA           mydomain.com               myIPv6address
AAAA           mail                                 myIPv6address    (set to DNS only – NO PROXY)

I wanted the mail IPv6 to be visible for mail servers to be able to verify the actual IPv6 and then it can run a reverse DNS on that IPv6 and verify that it points to the mail.mydomain.com (I can set the reverse DNS from the vultr website where I have my VPS).

I checked that things were working for both IPv4 and IPv6 using this tool

I definitely am a noobie when it comes to DNS settings, so I am not 100% sure that the way I configured things is the best method.  But it seems to be working for now.

I almost had the correct solution earlier when I added AAAA records and IPv6 addresses into my DNS settings.  Unfortunately, Cyberpanel does not natively support IPv6.  I only found this out when I was trying to access the website while out of my house.  My home wifi will use IPv4 by default apparently.  My cell service will use IPv6 when available.  I was getting frustrated trying to troubleshoot why my website seemed down when I was out of the house, but I was able to reach it just fine through a VPN.  At first I thought that it was a new Jetpack security plugin that was blocking my phone IP address, as an explanation why the site could be accessed fine from a VPN but not without.  After looking up the error messages as to why my site was unreachable without the VPN, one suggestion was to check and make sure my DNS records are correct.  I removed the AAAA records I had created earlier, and then I was able to access my website again.  It was only a fluke that my cell phone used IPv6 and I noticed this issue.  Otherwise I may never have known that anyone would get a site unreachable error if their network was trying to use IPv6.

Next I had to figure out why IPv6 settings which looked accurate were not working.  I came across some messages on the cyberpanel forums saying that IPv6 is not natively supported, but you can add it by following the steps I listed above.  Unfortunately, any additional sites I add, I will need to manually add to the IPv6 listeners.

So the next question is, do I need to do that for my other websites which do not use email?  I’ll have to put some more thought into it and see.

This issue came up again when I created a new forum on my server, and the registration emails were not going through to gmail – getting the IPv6 warning message in the title of this message. Hopefully everything works as it is supposed to now.  And I did learn a little about IPv6 and DNS settings and Cyberpanel in the process.

3 thoughts on “550-5.7.1 Our system has detected that this message does not meet IPv6 sending guidelines regarding PTR records and authentication”

  1. Hello, thank you so much for this. But I still have an issue. I still get “No Reverse DNS can be found!” I am pretty sure i followed all steps.

    1. Can you provide some more details and I’ll see what I can find. I assume you followed the steps I had to above with ipv6 to setup reverse dns? And had you already setup reverse dns for ipv4? Also, where are you seeing the error message that no reverse dns is found?

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