What’s the difference between validation and verification?

Validation checks whether an address could be deliverable: proper syntax, valid domain, apparent mailbox existence. It's predictive, indicating likelihood of successful delivery based on technical checks.

Verification confirms actual delivery by sending a message and observing results. Double opt-in is verification: you send a confirmation email and verify it was received through subscriber action.

Validation is pre-send risk assessment; verification is post-send confirmation. Both serve list hygiene but at different stages. Validate before adding to lists; verify through confirmation workflows. They're complementary approaches, not alternatives.