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.

A blacklist is a database that contains IP addresses and domains that have been flagged for spreading harmful or unwanted emails. Such lists are mostly used by email service providers as one of the reasons to reject your emails from reaching the prospect’s 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.