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Have you ever sent an email to someone and not received a reply? Perhaps you’ve wondered why your email went unanswered. It may be that the recipient was simply busy or didn’t see the email, but it could also be that the recipient’s email server blocked the email. One way in which an email server blocks emails is by using a blacklist. This blog post explains what an email blacklist is and how you can avoid being blacklisted yourself.
What is an email blacklist?
An email blacklist is an extensive database containing public domains and IP addresses that have been flagged as suspicious for sending spam emails over the internet. It is also known as a DNSBL (Domain Name System-based Blackhole List) or RBL (Real-time Blackhole List). Organisations such as email service providers (ESPs), internet service providers (ISPs) and anti-spam agencies (ASAs) use this list to detect, track and block spam emails entering their networks.
Have I been blacklisted?
There are several signs that indicate the status of your IP address. If you are blacklisted, you will not be able to send emails properly to the recipient’s inbox. However, this does not mean that you will be blacklisted by every mail server in the world. If you appear on the blacklist of one DNSBL service, there are hundreds of others that may not have blacklisted you. Some key indicators:
- The number of lost emails has increased
- Experiencing a decline in delivery rates
- Experiencing a high number of email bounce rates
These do not confirm that you have been blacklisted, but they are warning signs. If a few of the boxes relating to delivery issues are ticked, you can now check whether this confirms that your domain or IP address has been blacklisted.
Checking an IP address and domain in an email verifier
There are various email blacklist services available on the internet. It is impractical to check them all, but some applications maintain a list of active RBLs (real-time blackhole lists) to save you time. They provide a page dedicated to the specific RBL service and also offer a service to have the domain or IP address removed from the list.
Here are some popular RBL applications:
- MXToolBox: This tool checks whether a domain has been blacklisted by checking against several RBL lists. It provides detailed information and recommendations regarding the domain’s current status.
- MultiRBL: This is a free DNSBL search site that can scan over 100 DNSBL lists to check whether a domain has been blacklisted. It also provides detailed instructions on the steps required to remove your domain from the blacklist.
Malicious websites can be added to Google Safe Browsing’s blacklist, which warns visitors about potentially unsafe sites. Dropmysite includes a feature that sends you an alert if your website appears on this blacklist monitoring service – so you can take corrective action straight away, before it’s too late!
Blacklists are an important tool for email deliverability. They help protect email users from spam and phishing emails, and improve the deliverability of legitimate email campaigns. If you are unfamiliar with blacklists, or are unsure whether your IP address is listed on them, we recommend using a blacklist checking tool. Use this information to refine your email practices and improve your chances of having your emails delivered to the inbox.