How can we solve this?
mx.google.com
Remote Server returned '550-5.7.1 [2605:e000:5b0c:b600:217b:9d84:ff0f:e17a] 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=ipv6_authentication_error
for more 550 5.7.1 information. t10si67058629pfa.174 - gsmtp'
bostjanc
