What's an Open Relay SMTP Server and Why Should You Avoid It?

An open relay SMTP server is a contact server that allows anyone to send emails through it, regardless of their origin. This kind of server does not restrict access, meaning it may be used to send emails from any address, even though the sender isn't authorized. While open relay servers were once common in email systems, they pose significant risks to both security and email deliverability.

Security Risks of an Open Relay SMTP Server
Open relay SMTP servers are highly vulnerable to abuse by spammers. Since they don't really verify the sender's identity, malicious actors can exploit these servers to send unsolicited emails, or "spam," without revealing their true identity. This results in an important escalation in spam traffic and can quickly cause the server being blacklisted by email providers. Once blacklisted, emails sent from your own server may be flagged as spam, impacting your communication efforts.

How to Prevent an Open Relay SMTP Server
To avoid turning your SMTP server into an open relay, it's necessary to configure it with proper access control settings. Make sure that only authorized users can send emails through your server. Additionally, consider implementing authentication mechanisms such as for example SPF (Sender Policy Framework) and DKIM (DomainKeys Identified Mail) to verify the legitimacy of outgoing emails.

Conclusion
Maintaining a safe SMTP server is vital for safeguarding your network against unauthorized use and maintaining the trustworthiness of your email domain. By ensuring your SMTP server isn't an open relay, you protect one's body from being exploited by spammers, improve email deliverability, and ensure smooth communication for your business.

For more information on the best way to secure your SMTP server, contact we of experts today!