A blacklist is a list used by various online services, especially email providers and internet service providers, to block entities believed to engage in harmful or suspicious activities. It typically includes IP addresses, email addresses, or domain names known to send spam, distribute malware, or other security infractions.
Being on a IP blacklist can severely impact the ability to send emails, as messages from blacklisted addresses are likely to be rejected or filtered by receiving servers.

It’s a diagnostic tool that checks if your mail server IP address has been listed on any DNS blacklists, which can affect your email deliverability and reputation.

IPs can be blacklisted due to suspected spamming activity, being part of a botnet, or sending emails to honeytrap addresses, or receiving excessive spam complaints.

Removal processes vary by blacklist but generally involve sending a removal request after addressing the issues that led to the listing.

Being on a blacklist can trigger spam filters and lead to your emails being blocked or filtered by ISPs and email service providers, affecting your reach.

Yes, regular monitoring with tools like MailWizz’s Blacklist Check, following best email practices, and maintaining a good sending reputation can help avoid blacklisting. Additionally, actively managing and responding to spam reports can help identify and address issues that might otherwise lead to being blacklisted.