What is an IP Address Blacklist?
IP address blacklisting (sometimes referred to as blocklisting
) protects internet and web servers from potentially malicious attacks.
How Does IP Address Blacklisting Work?
Every device connected to the internet or internal network has a unique IP address
assigned to it. This number allows internet requests to pass from one server to the next until they reach their destination.
If a website or server is considered a potential security risk, the IP address associated with it can be blacklisted. This blocking can be done through firewall rules or by blacklist databases.
Firewall rules are usually created by a company's system administrators. Since blocking impacts a company's exchange of communications, it is important that these rules are carefully applied.
Blacklist databases such as Spamcop
are continuously updated based on identified threats. These databases are commonly called Realtime Blacklists
(RBL or DNSBL).
What is a Whitelist?
As its name implies, a whitelist is list of permitted IP addresses. This list is most often used to ensure specific IP addresses can be reached.
How Does Email Blacklisting Happen and How to Prevent It?
Spam is an unfortunate byproduct of email. Internet service providers (ISPs) continually monitor emails through spam filtering and blacklists to protect users and reduce harmful emails.
Companies put themselves at risk when they don't adopt and follow appropriate email policies. This is especially critical when doing email campaigns or mass emails.
Here are some tips to protect your company's reputation and ensure proper email delivery include ---
Never send mass emails directly from your computer's email client such as Outlook. A sudden surge in email traffic from your account can look like spam to your ISP's mail server.
Always use an established email marketing service such as Mailchimp or Constant Contact for your email campaigns. These services manage the proper flow of your emails and enforce legal compliance.
It should be obvious and yet it happens far too often. Never add an email address to your mailing list without permission. Recipients can flag your email as spam, landing your company on a blacklist or being banned from an email service.
For an added layer of protection and goodwill with your recipients, implement a double opt-in for new subscribers.
Regularly clean your mailing list. For example, you might want to remove recipients who never open your emails. At some point, they might flag these emails as annoying or unwanted even if they subscribed at some point.
Do a periodic subscriber confirmation email. Give inactive subscribers the opportunity to unsubscribe.
Include an easy to unsubscribe link or button in every email campaign. This is a legal requirement of the CAN-SPAM act.
How to Plan an Email Campaign Workbook (docx)
MXToolkit IP Blacklist Check
Spamcop IP Blacklist Check
Spamhaus IP Blacklist Check
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