[BlueOnyx:23079] Gmail problems... again

[Lewis Gardner]

Greetings!

I have had this problem before. Mail from a BlueOnyx 5209R connected via 
Spectrum has problems sending email to addresses at gmail.com:

> The original message was received at Wed, 31 Jul 2019 01:28:13 -0400
> from b0.xxxx.org [96.11.xx.xx]
> 
>    ----- The following addresses had permanent fatal errors -----
> <xxxxx at gmail.com>
>     (reason: 550-5.7.1 [2607:fcc8:a28b:1700:a6bf:1ff:xxx:xx] Our system has detected that)
> 
>    ----- Transcript of session follows -----
> ... while talking to gmail-smtp-in.l.google.com.:
> 
>             DATA
> 
> <<< 550-5.7.1 [2607:fcc8:a28b:1700:a6bf:1ff:xxx:xx] Our system has detected that
> <<< 550-5.7.1 this message does not meet IPv6 sending guidelines regarding PTR
> <<< 550-5.7.1 records and authentication. Please review
> <<< 550-5.7.1  https://support.google.com/mail/?p=IPv6AuthError for more information
> <<< 550 5.7.1 . c3si83455555ioq.99 - gsmtp
> 554 5.0.0 Service unavailable

Another BlueOnyx 5209R connected at a co-location site has always been 
able to send email to gmail.com addresses without problem.

When I brought this issue up before the solution was to run the 
following two commands:

> sysctl -w net.ipv6.conf.all.disable_ipv6=1
> sysctl -w net.ipv6.conf.default.disable_ipv6=1 

However that does not seem to have the same joyful effect.

Any ideas?

TIA