To date, the problem of spam email messages is becoming more global. The number of advertising emails is growing each month and already significantly exceeds the number of ordinary emails we get used to receive. Spam is a problem that surely refers to everyone who actively uses their mailbox. Registering on the forum, writing a comment, or placing the order on a webshop is enough for your email address to get into the hands of a spammer. It is known that even the most reliable providers can have a “leak” of mail address databases.
No matter how much you hide your email address, it is pretty difficult to protect yourself from spam without using specialized programs for that purpose. Of course, this problem is especially acute for those whose work is connected to the Internet and who simply have to provide their email address on the web pages so that they can be contacted.
The Problem of Spam – How to Avoid It?
Since spam is a problem that has arisen since quite a long time, today there is a large number of software solutions designed to combat it. Some utilities have a constantly updated database of “blacklisted” email addresses of spammers. So once detecting messages from “non-wanted” contacts, they simply delete them. On the contrary, other utilities offer the user to create a list of “good” email addresses. Thus, the rest of the messages are blocked. What are the methods of combating spam? What spam free tools for anti spam protection can help you solve the problem of your overcrowded mailbox?
There are two main methods for protecting the mail server from spam:
- spam protection at the stage of email delivery to the mail server;
- spam “separation” after it is received by the mail server.
When it comes to the first approach, the most popular methods of spam combating are the following ones:
- the use of blackList DNS (DNSBL), greylisting, and various delays in “receiving” mail;
- the use of various technical means such as checking the existence of the user in your contact list;
- checking the “correctness” of the sending server by methods such as the presence of a record in the reverse DNS zone, the SPF record, etc.
Among the other methods of analyzing the contents of an email, performing a check by various algorithms, such as searching for special keywords of an advertising character, is most popular. So, let’s take a closer look at these e-mail filtering methods.
Black lists or DNSBL (DNS BlackLists)
Blacklists contain the email addresses that may send spam to your mailbox. Widely used lists are “open relayers” and “open proxies,” as well as various lists of dynamic addresses that are allocated by providers to end-users. Due to the ease of implementation, these blacklists are used through the DNS service and ensure safe email sorting.
Gray Lists or Greylisting (Greylisting)
The principle of gray lists (Greylisting) is based on the tactics of sending spam. As a rule, spam is sent in a very short time in bulk from any server. The work of the gray list consists of deliberately delaying the receipt of emails for a while. In this case, the address and the time of transfer are recorded in the gray list database. If the remote computer is a real mail server, then it must keep the message in the queue and repeat the transfer within five days. As a rule, spam bots do not keep emails in the queue, so after a short time, they stop trying to forward the letter.
Efficiency Analysis
The first two methods allow you to filter out about 90% of spam even at the stage of email delivery to the mailbox. As an alternative solution, the already delivered emails can be marked as spam with special programs for content sorting.