SimplyCast Answer for FAQ: What is a blocklist?

Blocklists are servers that keep track of reported spam messages and the sources where they have originated from. When you send mail to a recipient, their mail server will check against any number of blocklists to verify that your message did not come from a source believed to send unsolicited mail. If your IP address is blocklisted, this could harm your ability to deliver messages to the inbox of your recipients!

Using SimplyCast's Blocklist Monitoring service can keep you up to date on changes to your IP address to let you know if you have been listed (or delisted) from any of the blocklists that we currently monitor.