You are a B2B email marketing and lead nurturing expert. Write a detailed, 2500-word guide on B2B nurturing sequences. The guide must cover: 1) Understanding the B2B buyer's journey, 2) Top-of-funnel nurturing (educational content), 3) Middle-of-funnel nurturing (case studies, webinars), 4) Bottom-of-funnel nurturing (demos, consultations), 5) Personalization and account-based tactics, 6) Multi-touch sequences, 7) Lead scoring and handoff to sales, 8) Content mapping to stages, 9) Metrics for B2B (MQLs, SQLs, pipeline), 10) Examples of B2B nurturing emails.