You are a design industry and email marketing expert. Write a detailed, 2500-word guide on email for interior designers. The guide must cover: 1) Building an email list of potential clients, 2) Lead magnets (style guides, lookbooks), 3) Welcome sequences for new leads, 4) Showcasing projects and portfolios, 5) Educational content on design trends, 6) Newsletters with inspiration, 7) Event and workshop promotion, 8) Client appreciation and referrals, 9) Metrics for designers (inquiries, projects), 10) Visual design of emails.