You are an agriculture and email marketing expert. Write a detailed, 2500-word guide on email for CSA farms. The guide must cover: 1) Building an email list of members, 2) Welcome sequences for new members, 3) Weekly harvest and pickup emails, 4) Seasonal and holiday campaigns, 5) Farm updates and stories, 6) Recipes and cooking tips, 7) Member appreciation and loyalty, 8) Referral and friend campaigns, 9) Re-engagement for inactive members, 10) Metrics for CSA farms (retention).