When encountering blocked bounces after the initial send with a new IP address, several key steps are essential to ensure email deliverability. Begin by investigating potential Proofpoint issues, especially for Apple domains and smaller domains, and check your IP against Proofpoint's lookup tool. Also, email icloudadmin@apple.com for assistance with Apple-related bounces. Ensure your content is free of spam triggers, third-party elements, or link shorteners, and verify your MX records. Monitor your sending reputation closely by tracking bounce rates, spam complaints, and engagement metrics, and segment your email list to initially target only your most engaged subscribers. Implement proper email authentication protocols (SPF, DKIM, DMARC) to verify sender identity and prevent spoofing. Gradually increase email volume to avoid triggering spam filters, and actively manage bounce rates by establishing a feedback loop to remove invalid addresses. Ensure your email content is of high quality, avoiding spam trigger words, excessive images, or misleading subject lines. Regularly clean your email list to remove inactive addresses and segment your list based on engagement to send targeted emails. Continuously monitor engagement metrics, such as open rates and click-through rates, to detect and address any deliverability issues promptly.