Act as a seasoned email marketing strategist with 10+ years of experience in optimizing newsletter performance. Provide a detailed, data-backed guide on the best ways to determine the optimal send times for [TYPE OF NEWSLETTER] (e.g., B2B, B2C, niche industry) targeting [AUDIENCE DEMOGRAPHIC] (e.g., millennials, executives, freelancers). Include factors like time zones, industry benchmarks, and [PLATFORM-SPECIFIC CONSIDERATIONS] (e.g., Gmail, Outlook, mobile vs. desktop). Offer 3-5 actionable strategies, such as A/B testing send times or leveraging analytics from [TOOL NAME], to improve open and click-through rates. Use real-world examples and avoid generic advice.