The server that works the most within your data center is the mail server, probably. The traffic passing through it is very high, which leads us to the challenge of keeping your sensitive information protected. As we know, a protected mail server is not an option nowadays. It is not a luxury. It is a necessity!
Based on our experience, we have selected 9 tips on how to best protect your mail server. We really hope it helps you.
1. Mail relay
Pay attention to setting up mail relay options so that it does not become an open relay, which allows fraudsters to use your mail server to send spam and apply scams. Define which IP addresses or domains are allowed to relay email.
Configure the SPF (Sender Policy Framework). It is a TXT type record that allows you to determine which IP addresses can send emails from your domain.
As the SPF, the DKIM (DomainKeys Identified Mail) is an email authentication protocol and a TXT type record. The DKIM mechanism is based on encryption, a fingerprint hash, which validates the email so that the receiving mail server identifies the sender. Setting it up correctly, you will have one more protection weapon at your favor.
DMARC (Domain-based Message Authentication Reporting & Conformance) uses SPF and DKIM protocols to ensure even more security in message authentication, providing reporting from receivers to senders. This way you monitor your domain and improve your mail server protection.
5. Reverse DNS
The Reverse DNS is also known as a PTR record. Once configured, Reverse DNS checks if the sender's IP address matches the host and domain names.
DNSBL (Domain Name System Blacklists), also known as DNS Blacklists, are spam-blocking lists that allow you to keep your server free of spam and threats. The more connections with DNSBL, the better.
SURBL (Spam URI Real-time Black List) is also a spam detection method, similar to DNSBL. It is a list of URIs that in some moment have appeared in unsolicited messages. If you have a SURBL filter, you prevent different types of attacks.
8. Local IP blacklist
You should have a local IP blacklist on your mail server, since targeted attacks, such as spear-phishing, are on the rise.
9. SSL e TLS
TLS (Transport Layer Security) and SSL (Secure Socket Layer) are your best friends when using POP3 encryption and IMAP authentication, since they are security protocols that authenticate messages.