Malware programs are downloaded onto computers
Posted: Thu Feb 13, 2025 9:00 am
The software is linked to the mail server and performs further analysis of the message content (both headers and body), looking for IP addresses and domains that appear as URLs in the received lines and body, and checking them against SBL, XBL, and DBL databases. Many times the results of these checks are combined with other checks to establish a "spam score" for the message, which is then used to decide whether to deliver the message to a regular user mailbox, a separate folder, or to throw it away completely.
All three of these components should be considered absolutely essential. No new installation should be done without these three components.
Prevent outbound spam
Spamming is caused by individuals or units within your organization who decide to send spam, or by security issues ig database that allow others to send spam from your IP address. There is no technical solution to the first case, however, all employees working in marketing should be fully aware that all email addresses used for bulk mailing should have an explicit request to receive emails about your products or services through a confirmed opt-in process.
The vast majority of spam caused by security issues falls into one of four (sometimes overlapping) categories:
Malware Trojans and Viruses
using a variety of tricks and are then used by criminals for a variety of nefarious tasks. Sending spam is just one of them.
Trojans can have a direct negative impact on your legitimate mail flow. Basically you should not allow any machine that is not a mail server to initiate SMTP connections (port 25 as a destination) to external hosts. Only mail servers should be able to send mail. This measure will completely render Trojan programs that bypass mail servers ineffective.
While it's always a good thing to have antivirus software scanning your machine, many malwares these days manage to evade detection by constantly changing. The best thing to do is to set something up so they can't get through your firewall and send mail outside.
Open the relay
Your mail system should not behave as an open relay , i.e. allow anyone in the world to connect to the server and send mail to anyone in the world. The main problem is that today's firewalls and other protection boxes are usually responsible for open relay settings, not the mail server itself. But testing for open relay is very simple and should be done every time you modify your mail system configuration. If the test passes, you don't have this problem.
Stolen Accounts
A very common reason for spam to be emitted from your mail server is the presence of a password known to spammers, either through guessing, phishing, or malware espionage. Control the strength of your users' passwords and make sure your server writes the account name to the log whenever it sends mail using SMTP AUTH authentication (unfortunately, some mail server software products do not do this with the default configuration). It also helps to include the account information in the headers of outbound mail.
If your mail server allows it, define a limit on the number of messages each user can send using authentication within a certain period of time.
All three of these components should be considered absolutely essential. No new installation should be done without these three components.
Prevent outbound spam
Spamming is caused by individuals or units within your organization who decide to send spam, or by security issues ig database that allow others to send spam from your IP address. There is no technical solution to the first case, however, all employees working in marketing should be fully aware that all email addresses used for bulk mailing should have an explicit request to receive emails about your products or services through a confirmed opt-in process.
The vast majority of spam caused by security issues falls into one of four (sometimes overlapping) categories:
Malware Trojans and Viruses
using a variety of tricks and are then used by criminals for a variety of nefarious tasks. Sending spam is just one of them.
Trojans can have a direct negative impact on your legitimate mail flow. Basically you should not allow any machine that is not a mail server to initiate SMTP connections (port 25 as a destination) to external hosts. Only mail servers should be able to send mail. This measure will completely render Trojan programs that bypass mail servers ineffective.
While it's always a good thing to have antivirus software scanning your machine, many malwares these days manage to evade detection by constantly changing. The best thing to do is to set something up so they can't get through your firewall and send mail outside.
Open the relay
Your mail system should not behave as an open relay , i.e. allow anyone in the world to connect to the server and send mail to anyone in the world. The main problem is that today's firewalls and other protection boxes are usually responsible for open relay settings, not the mail server itself. But testing for open relay is very simple and should be done every time you modify your mail system configuration. If the test passes, you don't have this problem.
Stolen Accounts
A very common reason for spam to be emitted from your mail server is the presence of a password known to spammers, either through guessing, phishing, or malware espionage. Control the strength of your users' passwords and make sure your server writes the account name to the log whenever it sends mail using SMTP AUTH authentication (unfortunately, some mail server software products do not do this with the default configuration). It also helps to include the account information in the headers of outbound mail.
If your mail server allows it, define a limit on the number of messages each user can send using authentication within a certain period of time.