For me that IP belongs to apple, when using the iOS mail client. I presume Apple forces third party apps to use their API and then stuff like this happens. Gues

For me that IP belongs to apple, when using the iOS mail client. I presume Apple forces third party apps to use their API and then stuff like this happens. Guess that's also on google, not mitigating that issue, tho. Have you tried a VPN? I wonder, if Apple manages to expose IP despite a VPN. They had issues with stuff like that before.