If your IP has been blacklisted, you need to take action to remove it:
Identify the blacklist your IP is on using the tools mentioned earlier. Visit the website of the blacklist and follow their instructions for delisting. Address the root cause of why your IP was blacklisted. This may involve improving your email practices and ensuring you comply with anti-spam laws. Submit a removal request to the blacklist authority. This process can take time, so be patient.