IP Blacklists are real-time databases that identify IP addresses that are known to send spam or malicious content. They are defined by ISPs (Internet Service Providers) and specialized organisms and are used as references by email servers to determine if an incoming email can be trusted or not.
Email IPs that are blacklisted are likely to land in spam, as they have a history of negative behaviors.
Your IP has risks to be added to a blacklist if:
Good sending practices and active authentication protocols (SPF, DKIM and DMARC) can help you to reduce the risks to have your IP blacklisted.
Spam filters are using keyword detection to spot junk emails and make sure your inbox stays clean. This is why you should choose carefully the words used in the subject and body of your emails. Here's is the ultimate list of spam-trigger keyword that you should ban from your email content in 2021!