Spam is flooding inboxes, message boards, newsgroups, user comments, etc with the same message(s). The message is usually commercial advertising for quasi-legal products and services. Spam is lucrative because it costs the spammer little money to send. The brunt of the cost is borne by the recipients or carriers instead of the sender.
Email spam that is targeted at individual users can be more than just an annoyance. Spammers can distribute viruses through email messages sent to your inbox.
There are several ways to stop spam. We have outlined four methods here.
The first method for an organization is to install a corporate spam filter.
A corporate spam filter is installed on the receiving email server. There are two options for installing a corporate spam filter:
Install a spam filter with the SMTP server
The SMTP protocol is for sending email SMTP. This is the most direct and easiest method for installing a spam filter. The filter is installed on Port 25 where it inspects incoming email messages and then passes them on to the SMTP server that is listening on another port. The SMTP server then sends the message to the POP3 server, which forwards it to the email recipient.
Install a spam filter with the POP3 server
The POP3 protocol is for retrieving email. When a spam filter is installed on the POP3 server, email messages must still pass through the SMTP server. This may cause increased costs for data storage and handling.
The second method to stop spam is to contract with a third party organization. Using this method all email is directed to the third party's spam filter. Unsolicited bulk mail (spam) is deleted and the clean mail is redirected to the organization's recipient. In order for the organization's mail to go to the third party their MX (mail exchange) record must be changed at the Domain Name System (DNS).
The third method is to install a spam filter on your local computer. The majority of email clients can be configured to filter spam. Some of the configurations typically include:
Blacklist Senders
This configuration blocks a list of senders. Databases of blacklists are available on the Internet.
Whitelist Senders
This configuration allows the recipient to enter a list of email addresses that are allowed to pass through. All others are sent to the junk email folder.
Block Top Level Domain
Some spam filters can be configured to block email from regions and even entire continents known for distributing spam such as Eastern Europe.
The final method is to install a separate spam filtering software. The software works with your email client to eliminate junk mail. This software may need to be "trained" meaning that the user must identify the unsolicited messages they receive as spam. The filtering software then uses the characteristics of the spam messages to identify and block unwanted email.
