I see this crate uses nightly rust for ip.is_global operation.

It prevents me from using this crate. However, I do think this crate is way more engineered than email-addresses crate from both the module organization and tests.

Can we make copy the implementation of is_global from std to make it able to be used in stable rust?

Or we add a feature to don't validate_deliverability since someone may not want network operation(DNS queries) when using this library.

BTW, I find that trust_dns_resolver crate is moved to hickory_resolver.

If you like it, I can make a PR.