It's likely not about ipv6, but instead it's about your ipv4 having bad reputation in the past. Basically you changed your source address to a cleaner one.
It's likely not about ipv6, but instead it's about your ipv4 having bad reputation in the past. Basically you changed your source address to a cleaner one.
My current IP shows "0 - low risk" with that tool. Grabbing a random PIA IP shows "93% - Abusive IP" with a warning about being a high risk proxy connection. The random VPN IP is also on SPAM blocklists.
I'm guessing a huge portion of cheap shared hosting is the same.
Edit- The IP my employer uses as its outbound nat IP that we vpn from while WFH (so it actually is a proxy) gets a clean bill of health while our corporate email server (not a proxy at all) is tagged as one.
It very well could be. That wasn't an endorsement by any means. The problem from what I can see is if services like that are convincing CTOs to use their lists it becomes relevant (even if the info isn't accurate).
If you're running a serious mail service your IPs don't change that much. Not only will you have a pool of IP addresses just for that reason, you'll also likely need a few unused ones for when one of your users tanks your reputation and you have to roll them.
Nobody taking real money for email will use a randomly assigned IP as source. (unless it's randomly selected and then tested for reputation before use) Mailgun and other services even allow you to book a dedicated IP just for your outgoing emails.