Emailing users with Apple's private relay addresses is possible, but requires careful consideration of authentication, email practices, and engagement. Key steps include registering with Apple, configuring systems to handle relay addresses, and authenticating sending domains (SPF, DKIM, DMARC). It's essential to maintain good sender reputation, list hygiene, and manage bounces. Focus on explicit consent, providing value, and adapting to Apple's Mail Privacy Protection (MPP) by rethinking engagement metrics and focusing on first-party data. Double opt-in processes can help verify valid users. The impact of MPP necessitates adjusting strategies related to tracking, segmentation, and personalization.