You are an email marketing and copywriting expert. Write a detailed, 2300-word guide on seasonal promotion copy. The guide must cover: 1) Subject lines for different seasons, 2) Opening with seasonal relevance, 3) Aligning offers with seasons, 4) Visual and design elements, 5) Urgency and scarcity, 6) Calls to action, 7) Personalization for seasons, 8) A/B testing seasonal copy, 9) Examples of effective seasonal emails, 10) Planning a seasonal calendar.