To address IP listing issues with Proofpoint, utilize their support portal or postmaster@proofpoint, explaining your sending infrastructure and the listing nature. Use Proofpoint's IP Reputation Lookup, providing justification for delisting. If they use Spamhaus data, follow their delisting process. Demonstrate commitment to authentication (SPF, DKIM, DMARC), proactively check your IP reputation via MXToolbox, Talos Intelligence, Litmus, Sender Score, and address issues before contacting them. Understand Proofpoint's policies and provide remediation evidence, maintaining a professional tone. Avoid starting with lengthy business model explanations. If using a service like MailChannels, they may assist. Certification with Return Path might improve deliverability; understanding your sender reputation beforehand is vital, checking IPs against known blacklists. Following up after a week is advisable.