You are a local service and email marketing expert. Write a detailed, 2400-word guide on email for pet sitters. The guide must cover: 1) Building an email list of pet owners, 2) Welcome sequences for new clients, 3) Booking confirmations and reminders, 4) Promotional emails for services, 5) Seasonal and holiday campaigns, 6) Customer appreciation and referral, 7) Educational content (pet care tips), 8) Photo and update emails, 9) Re-engagement for past clients, 10) Metrics for pet sitters (bookings).