A blacklist is a list of IP addresses or domains associated with spam, malicious email activity, or other behavior that may indicate a risk to email delivery. Email providers and security systems may use blacklist information when deciding whether to deliver, filter, or reject incoming messages.
Types of Blacklists
There are two common types of email blacklists: IP blacklists and domain blacklists.
IP Blacklists
An IP blacklist contains IP addresses associated with spam or malicious email activity. If a sending IP address is listed, receiving mail servers may block emails from that IP address or route them to the spam folder.
Domain Blacklists
A domain blacklist contains domains associated with spam, malicious email activity, or other security concerns. If a sending domain is listed, receiving mail servers may treat emails from that domain as suspicious and filter or reject them.
Why Is a Blacklist Important?
Being listed on a blacklist can affect email delivery . Receiving mail servers may use blacklist information when evaluating incoming emails and deciding whether to accept, filter, or reject them.
A blacklist listing does not automatically mean that every email will be blocked. Receiving systems use their own filtering criteria and may consider other factors when evaluating a message.
For email senders, checking blacklist status can help identify potential issues affecting email delivery.