• Blog
  • DNS toolbox
  • French
  • Offers
  • Linkedin
  • FAQ
  • …  
    • Blog
    • DNS toolbox
    • French
    • Offers
    • Linkedin
    • FAQ
broken image
broken image
broken image

 

  • Blog
  • DNS toolbox
  • French
  • Offers
  • Linkedin
  • FAQ
  • …  
    • Blog
    • DNS toolbox
    • French
    • Offers
    • Linkedin
    • FAQ
    Request a Free Trial
    • Blog
    • DNS toolbox
    • French
    • Offers
    • Linkedin
    • FAQ
    • …  
      • Blog
      • DNS toolbox
      • French
      • Offers
      • Linkedin
      • FAQ
    broken image
    broken image
    broken image

     

    • Blog
    • DNS toolbox
    • French
    • Offers
    • Linkedin
    • FAQ
    • …  
      • Blog
      • DNS toolbox
      • French
      • Offers
      • Linkedin
      • FAQ
      Request a Free Trial
      broken image

      Preventing Spam Email from Your Network

      · cybersecurity,DMARC,delivery

      When analyzing DMARC (Domain-based Message Authentication, Reporting, and Conformance) reports, it’s not uncommon to discover that IP addresses owned by large, reputable companies are being flagged for sending spam. This revelation might seem surprising, but the root cause often lies in compromised systems within their networks.

      How Malware Leads to Spam Email

      Hackers frequently exploit security vulnerabilities by infecting computers with malware, turning them into part of a botnet—a network of infected devices controlled remotely. These botnets are then leveraged to send spam emails globally, tarnishing the reputation of the affected IP addresses.

      A compromised system sending spam can cause an organization's public IP address to become blacklisted, affecting legitimate email communications and the company’s overall credibility.

      Tactics to Prevents Spam Email from Your Network

      1. Configure Your Firewall to Block Outbound Port 25

      A key strategy to prevent your network from inadvertently sending spam is to restrict outbound connections to port 25. Port 25 is traditionally used for SMTP (Simple Mail Transfer Protocol), which facilitates the sending of emails. While legitimate email servers use this port, so do malicious botnets attempting to distribute spam. This will prevent infected computers in your network from sending emails directly without authentication.

      broken image

      If you operate mail servers that need to send emails using port 25, explicitly allow outbound traffic from only these servers. Carefully manage these exceptions to ensure they are not exploited.

      2. Strengthen Endpoint Security

      • Deploy anti-malware solutions across all devices in your network to reduce the likelihood of malware infections.
      • Conduct regular security audits and update software to patch vulnerabilities.

      3. Monitor and Audit Network Traffic

      • Regularly review DMARC reports to identify any unusual activity, such as unexpected email-sending patterns from unauthorized systems.
      • Implement network monitoring tools to detect and address anomalies promptly.

       

      Fed up with phishing, spam, deliverability issues, and cryptic DNS configurations? Explore our managed service plans, customized to fit your unique needs!

       

      Previous
      Revolutionizing DMARC Analysis: Unmatched Detection and...
      Next
      Why Are PTR Records Important?
       Return to site
      Profile picture
      Cancel
      Cookie Use
      We use cookies to improve browsing experience, security, and data collection. By accepting, you agree to the use of cookies for advertising and analytics. You can change your cookie settings at any time. Learn More
      Accept all
      Settings
      Decline All
      Cookie Settings
      Necessary Cookies
      These cookies enable core functionality such as security, network management, and accessibility. These cookies can’t be switched off.
      Analytics Cookies
      These cookies help us better understand how visitors interact with our website and help us discover errors.
      Preferences Cookies
      These cookies allow the website to remember choices you've made to provide enhanced functionality and personalization.
      Save