Blacklisting

Blacklisting means blocking incoming messages from certain senders (by domain or IP) which usually happens if your emails get flagged as spam.

As a result, all of the emails from that sender will inevitably land in the spam folder and not in the inbox.

Blacklist check is a part of any deliverability testing procedure and can be performed using tools like mail-tester.com.

To get off most blacklists, you will have to reach out to the blacklist operators directly and prove that you’re not a spammer, i.e., strictly follow the email best practices for some time to make sure you don’t get reported again while on probation.