Recovering a poor Gmail sender reputation is a multifaceted process that can take anywhere from a few days to several months, depending on the severity of the issue and the corrective actions taken. Key steps include identifying the root cause of the reputation decline (such as spam complaints, low engagement, or blacklisting), implementing proper email authentication (SPF, DKIM, DMARC), and consistently contacting Gmail's postmaster with updates. It's also crucial to adjust sending volume, starting low and gradually increasing it while targeting only the most engaged recipients. Maintaining excellent list hygiene by removing inactive addresses, implementing double opt-in, and avoiding spam traps is critical. Creating valuable and engaging content, monitoring bounce rates and spam complaint rates via Google Postmaster Tools, and addressing any blacklist issues promptly are also essential. Consistent monitoring of sender reputation, adherence to Gmail's bulk sender guidelines, proper email formatting, and considering a dedicated IP address are further considerations.