Definition - What does Blacklist mean?
A blacklist, in the context of computing, is a list of of domains or email addresses for which delivery of emails is blocked. When this occurs, a user is unable to send a message to the intended recipient. Email delivery management tools can be instituted to circumvent blacklisting.
Blacklisting also takes place when one IP address has been blacklisted. In these instances, the blacklisting can spread to other domains.
Techopedia explains Blacklist
The main reason for blacklisting is to block spam. The difficulty is filtering out the real spammers as compared to legitimate opt-in email marketers.
A big part of an email marketer's job is to get content through. Depending on the quality of the email list, collection practices, etc., staying off blacklists can range from a nuisance to a huge issue.