What is IP Blacklisting?

If your company uses email marketing, IP blacklisting is something to try to avoid. Blacklisting occurs when your IP address (or the IP address you share with others) is ignored by a web hosting company, so that any mail you try to send is blocked and not forwarded.

The Definition of IP blacklisting

Blacklisting happens for any number of reasons, most typically when an IP address is suspected of sending spam. Continual blacklisting will affect your IP reputation because your IP address will be identified as a regular source of spam. Owners of an IP are responsible for what comes out of that IP address, so it’s important to stop spam from originating to avoid a reputation for spammy behavior.

There are hundreds of blacklists out there, so if you’re wondering “Who is blacklisting my IP?” you will need to do some research.

A blacklist is a list of IP addresses or domains that are known sources of spam; often referred to as DNSBLs (Domain Name System Blacklists). The technology was built on top of DNS and most MTAs can be configured to reject or flag messages that have been sent from a blacklisted IP. It’s important to remember that a DNSBL is a medium and not a specific list or policy. Policy in this context refers to the criteria that a DNSBL applies to decide which senders should be blacklisted and which shouldn’t. The policy also includes criteria for being delisted and the process for communicating with blacklisted senders.

There are two main types of blacklists; IP-based and domain-based. The IP-based lists include addresses of sending servers that are known spammers. Domain-based URI Blacklists (URI DNSBLs) are lists of domain names that appear within the email body. This blacklist will look for the URLs within the body of the email to see if it contains a domain that has been identified as a source of spam.

Dealing with a blacklisting issue

If your IP is blacklisted, all email traffic will come to a complete halt — even legitimate mail. You need to figure out how to get off blacklists quickly so email delivery is maintained for users.

Reliable email delivery is crucial for business operations. When it comes to IP blacklists, an ounce of prevention is worth a pound of cure. There are steps you can take to avoid email blacklists, which are recommended best practices to keep email traffic flowing.

Find out more about IP blacklisting, why it happens, and how you can prevent being blacklisted.


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