Open Rates: Compare the open rates of emails in different languages to see which ones perform best. Click-Through Rates (CTR): Monitor CTR to gauge how engaging your content is across languages. Conversion Rates: Track conversions to measure how well your email campaigns drive desired actions. Unsubscribe Rates: Keep an eye on unsubscribe rates to identify any language-specific issues. Customer Feedback: Collect and analyze feedback from subscribers to improve future campaigns.