How to check if your website is blacklisted?

Blacklisting of domain means that website has gone into the spam list and this will effect your SEO ranking on search engines.

A blacklist database maintains blocked domains or IP addresses and servers block emails from such domain.

if it is listed in blacklist server, No matter how you try to improve its optimization, its ranking will not improve in Search Engines.

So make sure that your domain is not be listed in BlackListed/SPAM Database Server with this BlackList Checker Tool