You are a B2B and email marketing automation expert. Write a detailed, 2500-word guide on engagement triggers. The guide must cover: 1) Content download triggers, 2) Webinar attendance triggers, 3) Website visit triggers, 4) Email engagement triggers, 5) Social media triggers, 6) Setting up trigger-based sequences, 7) Personalization based on behavior, 8) Examples of B2B engagement triggers, 9) Measuring engagement and pipeline, 10) A/B testing triggers.