Spam is one of the biggest problems on the Internet. The "data garbage" spreads mainly via e-mail and has many unpleasant consequences. Private individuals and companies receive unwanted emails every day. The large volume of junk data sent via the Internet entails high costs and a great deal of time. The Spam House.org published on its website has an enormous amount of information about spam senders and operates a freely accessible RBL server. Various blacklists can be used to IP addresses and domain names of known spammers are blocked. Problems with e-mail delivery can occur if Spam House discontinues support for public DNS resolvers.
Types and effects of spam
Unsolicited mass e-mails are one of the typical types of Spam. The messages are sent to a very large number of recipients. As a rule, these are e-mail marketing campaigns and other advertising-related purposes. Commercial e-mails are also sent in large quantities via the Internet. The content of these emails includes offers for casinos, sexual enhancers, financial services and software. Other types include collateral spam, backscatter and Usenet spam. Spam or junk causes considerable damage in terms of international communication. The biggest problems are the additional data volumes and the time required to get rid of the spam. Reading and sorting out unwanted e-mails, often referred to as junk e-mails, takes a lot of time. In most companies, the Internet is not billed according to usage time, but according to data volume. A large amount of spam increases the amount of data and therefore also increases the company's monthly costs. The large number of spam mails increases the processing time of normal mails and this in turn has a negative effect on productivity. In the USA alone, unwanted emails cause over 22 billion US dollars worth of damage every year. For these reasons, there are many companies and organizations that take action against spam and maintain black and grey lists. Spamhaus.org is one of the best-known providers that operates a publicly accessible RBL server. A Real-time Blackhole List is a blacklist that can be queried in real time and can be used to classify spam emails.
What is Spamhaus.org?
Spamhaus is an international non-profit organization and was founded in 1998. Its headquarters are located in Geneva. The organization has set itself the task of tracking spam activities on the Internet and those responsible for them. In the "Records Of Known Spam Operations", Spamhaus publishes many important details about the spammers. They even name the spammers and publish some photos. This information comes from many different sources and most of it is publicly available. The information is only published if there are at least 2 sources to back it up. Based on this information, other users can decide whether to classify a particular email as spam. Spamhaus operates several DNS-based blackhole lists and real-time blackhole lists. It has one of the largest DNS infrastructures in the world. Spamhaus' network consists of more than 80 public DNSBL servers located in 18 different countries. Spamhaus' servers are mainly used by Internet email providers, corporations, governments and military networks. Many corporate email servers use these blocklists to Filter spam and thus ensure the integrity of e-mail communication. Spamhaus offers this entire service free of charge.
The Zen list of Spamhaus at a glance
The mail accounts of around 2 trillion Internet users are protected by the DNSBL lists of the Spamhaus organisation. The company employs independent investigators around the world. The various blacklists of Spamhaus can be used free of charge for non-commercial purposes. Up to 100,000 emails per day is the maximum limit. Spamhaus provides more than 50 public servers for this purpose. If you exceed this volume or use the lists commercially, you have to license the use at Spamhaus.
Spamhaus operates several blacklists
The Spamhaus Block List (SBL) contains numerous IP addresses from which the organization believes that you should not receive email for your own safety. The basis for the entries are various spam events and these are analyzed by Spamhaus and then entered into the database. The Exploits Block List (XBL) contains the addresses of hacked desktop PCs and servers that belong to a botnet. Spamhaus receives the XBL data from the open proxy entries of njabl.org and from the lists of cbl.abuseat.org.
The Policy Block List (PBL) lists IP addresses that are used by the large Internet Service providers (ISPs) have been classified as so-called dial-up ranges. Many experts are of the opinion that no mails should be sent directly from such addresses. Spamhaus itself does not define the IP addresses on the policy block list. This is done exclusively by the service providers themselves. The ZEN list (zen.spamhaus.org) is a combination of data from the 3 lists XLB, SBL and PBL. If you want to query all 3 lists anyway, you can query the ZEN list directly and save time.
A major problem that can arise from being listed on the DROP list (Don't Route Or Peer) is that officially registered IP networks of acquired or insolvent companies that are not currently in use can be hijacked via the BGP routes and misused for other purposes, such as spam or cyber attacks. You should always block addresses that are located at drop.spamhaus.org. The Domain As the name suggests, Block List (DBL) does not contain addresses, but domains. Only domains that are used for phishing purposes, for example, or that are advertised in spam emails are listed.
Anti-spam solutions
Anti-spam solutions are essential to combat the constant onslaught of spam emails. There are different types of anti-spam solutions that can help you keep your email inboxes clean:
- E-mail filterThese filters check incoming emails for suspicious content and block them if they are identified as spam. They analyze the emails according to certain criteria such as subject lines, sender addresses and keywords.
- BlacklistsThese lists contain IP addresses and domains that have been identified as sources of spam. If an email comes from an address on the blacklist, it is automatically blocked.
- WhitelistsIn contrast to blacklists, whitelists contain IP addresses and domains that are classified as trustworthy. Emails from these addresses are always delivered.
- Bayesian filterThese filters use statistical methods to classify emails based on patterns and characteristics. They learn continuously and improve their accuracy over time.
By combining these anti-spam solutions, you can significantly reduce the amount of spam emails in your inbox and make your email communication more efficient.
Client host and spam traps
A client host is a computer or server that serves as an intermediate station for emails. It plays an important role in email traffic as it receives, stores and forwards emails. A well-configured client host can help prevent the spread of spam by recognizing and blocking suspicious emails.
Spam traps are special email addresses used by anti-spam companies to identify spammers. These addresses are deliberately not used for legitimate communication, so any email sent to a spam trap is automatically classified as spam. When a spammer sends an email to a spam trap, their IPAddress and domain is placed on a blacklist. This helps to identify the source of the spam and block future spam emails from this source.
By using client hosts and spam traps, anti-spam companies can effectively combat spam and improve email security.
How to unsubscribe from a Spamhaus blacklist
If your IP address or the address of your provider is on a Blacklist from spamhaus.org your e-mails will be rejected. In such a case, you can either contact your provider or Spamhaus directly. Via the website of Spamhaus you can manually remove IP addresses and domains from the blacklists.
Visit the official website of Spamhaus. Click the link "Blocklist Removal Center" and you will be taken to a new page. You can use the "IP Address Lookup Tool" to check whether your IP address is blocked by Spamhaus. Simply enter your address and click on "Lookup". The "Domain Lookup Tool" checks whether a website is on the Spamhaus blocklist. Enter the address of your domain and click on "Lookup". Within a few seconds you will see which addresses are blocked. There is a link under each red entry, which you must click on. Another page will then open and you will see detailed information on the relevant blacklist. On this page you will also find a "Remove button" which you click on. On the next page you will find detailed information on what exactly happens when you remove the IP address from the blacklist. Read this information carefully and then check the box. Then click on the "Remove IP Address" button.
A window with a form will open and you must fill it out completely. Enter your IP address and e-mail address and select your country. You must also select whether you have a dynamic or static IP address and whether you have a personal computer or a server. In the last step, you must enter the displayed code in the form and click on the "Submit" button. Your request must also be verified. For this purpose, you will receive an e-mail from Spamhaus with a 5-digit code. Enter this code in the form and click on the "Finish" button. Your IP address will now no longer be blocked by Spamhaus. To unsubscribe a domain address from Spamhaus, you can use almost the same procedure.
In most cases, Spamhaus only provides a reference to the CBL Blacklist. Here you will usually receive helpful information as to why your IP address was blacklisted. You should obtain this information before you be sure to write down and then analyze how this happened. In some cases, a domain name and a URL is specified via which the spam was sent.
Spamhaus and CBL are currently among the most sensible anti-spam solutions, because the providers provide the providers with helpful information with which the spam dispatch can be analyzed and corrected immediately. The delivery is also very well organized within a few minutes.
How to avoid blacklisting?
A blacklisting of server IP addresses occurs in most cases by sending spam through misused login data or hacked websites. Often, users do not even notice that someone else is sending spam via their own domain.
But there are workarounds to stop getting blacklisted.
Modern web hosting companies like in our example the webhoster.com AG also check outgoing Emails from the server for spam, viruses and malware. For example, an email sent via a server with a registered domain does not reach the recipient directly, but is first routed via a so-called spam protection gateway, which checks the e-mail and then forwards it to the recipient.
If a mailbox is abused or spam is sent via the website, the gateway will not forward the email to the recipient, but will restrict the mail sending and inform the domain owner.
A Spam protection gateway ensures that almost only valid clean emails are sent to the recipients and that spam is not allowed at all. As a result, the IP addresses of the gateway have a very high reputation and e-mails usually do not end up in the spam folder of the recipient.
In this example, the service is included free of charge in all tariffs. The following is used Spame Experts Gateway, which normally costs about 5 euros per month and domain. The advantage of webhoster.de AG is the local evaluation in their own data center in Frankfurt am Main. As a Spamexperts partner, the provider operates its own cloud with many email gateways. The eMails are therefore not first sent to a Cloud Provider abroad, but in compliance with data protection regulations in the same Data Center in which the website is also located.
With such a solution, you will no longer be blacklisted and your emails will reach the recipient safely. A worthwhile investment and perhaps also a reason to switch if you are currently using the Management of your domainor the server are overwhelmed.
Link to product: Web hosting with spam protection gateway
Link to instructions: Spam protection gateway on Youtube
E-mail security and spam prevention
Email security and spam prevention are closely linked. To avoid spam emails and protect your email accounts, you should take the following measures:
- Use strong passwordsA strong password is the first step to securing your email account. Change your passwords regularly and use a combination of letters, numbers and special characters.
- Update your e-mail softwareMake sure that your email software is always up to date. Updates often contain important security improvements that protect you from new threats.
- Be careful with unknown sendersDo not open emails from unknown senders and do not click on suspicious links or attachments. These could contain malware or redirect you to phishing websites.
- Use anti-spam softwareInstall reliable anti-spam software that detects and blocks suspicious emails. This software can help you keep your inbox clean and your email communication more secure.
- Report spam e-mailsIf you receive spam emails, report them to your email provider or to anti-spam companies such as Spamhaus. This will help to identify the source of the spam and prevent future spam emails.
By implementing these measures, you can significantly improve your email security and reduce the amount of spam emails in your inbox.
