Is buying email lists legal in the UK?

It is high-risk and best avoided. "Verified B2B email lists" sold by third parties are usually a mix of scraped corporate addresses, individual subscribers, and fabricated records — and buying one shifts you from "legitimate interest in good faith" to processing unlawfully sourced data.

It also undermines your legitimate-interest balancing test, which depends on contacts being researched rather than bulk-acquired. Build lists yourself from ICP criteria and verify them, rather than buying.