A: What's up again, juan_macar!

Yes, when you import we assume you have consent so subscribers don't need to double opt-in again.

Generally-speaking about double opt-in, our primary reason for double opt-in is to be GDPR compliant, and California privacy law compliant. I doubt in the near future email senders will be able to send emails to non-confirmed contacts anymore. There are too many consumer-focused regulations going in place that double opt-in I predict will be a necessity.