Introduction
Email security is critical in protecting your domain from threats like spoofing, phishing, and unauthorized access. By implementing key email authentication protocols, you can safeguard your emails and ensure they are trusted by recipients. This guide covers the essential protocols you need to know and implement:
Key Protocols for Email Security
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SPF (Sender Policy Framework):
SPF allows you to specify which mail servers are permitted to send emails on behalf of your domain. Properly implementing SPF helps prevent unauthorized sources from sending fraudulent emails using your domain.
Learn more about SPF and how to implement it. -
DKIM (DomainKeys Identified Mail):
DKIM adds a digital signature to your emails, allowing recipients to verify that the email was sent from your domain and has not been altered during transit.
Explore DKIM and its implementation. -
DMARC (Domain-based Message Authentication, Reporting, and Conformance):
DMARC builds on SPF and DKIM by specifying what should happen if an email fails authentication checks. It also provides reports to monitor and improve your email security.
Read about DMARC and its setup process.
Additional Email Security Protocols
MTA-STS (Mail Transfer Agent Strict Transport Security)
What is MTA-STS?
MTA-STS (Mail Transfer Agent Strict Transport Security) is a protocol that ensures emails sent to your domain are transmitted securely using TLS (Transport Layer Security) encryption. It helps protect against downgrade attacks, where an attacker forces a connection to fall back to an unencrypted state, and man-in-the-middle attacks, where an attacker intercepts and possibly alters communication between two parties.
How MTA-STS Works
When a sending email server communicates with a receiving email server that has MTA-STS enabled, the sender checks the MTA-STS policy published by the recipient domain. This policy is stored in a DNS TXT record and directs the sending server to require TLS for the email transmission. If a secure TLS connection cannot be established, the email is not delivered.
Implementing MTA-STS
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Create the DNS TXT Record:
- Publish a TXT record at
_mta-sts.yourdomain.comwith the following content:
- Publish a TXT record at
TLS-RPT (SMTP TLS Reporting)
What is TLS-RPT?
TLS-RPT (SMTP TLS Reporting) is a protocol that allows domain owners to receive reports about issues encountered during the establishment of TLS connections between email servers. These reports help administrators monitor the security of their email transmissions and address potential problems, such as failed TLS handshakes or misconfigurations.
How TLS-RPT Works
TLS-RPT works by publishing a DNS TXT record that specifies the email address where reports should be sent. When a sending server encounters issues with establishing a TLS connection, it generates a report and sends it to the specified address. The reports are usually in JSON format and contain details about the nature of the TLS issues.
Implementing TLS-RPT
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Create the DNS TXT Record:
- Publish a TXT record at
_smtp._tls.yourdomain.comwith the following content:
- Publish a TXT record at
BIMI (Brand Indicators for Message Identification)
What is BIMI?
BIMI (Brand Indicators for Message Identification) is an emerging email authentication standard that allows organizations to display their brand logo next to authenticated emails in the recipient’s inbox. BIMI enhances brand visibility and increases trust in the email's legitimacy by providing a visual indicator that the email is genuine.
How BIMI Works
BIMI relies on existing email authentication protocols like SPF, DKIM, and DMARC. To display the brand logo, the domain must pass DMARC authentication with a p=quarantine or p=reject policy. The logo is hosted as an SVG file and referenced in a DNS TXT record. The recipient's email provider then fetches the logo and displays it in the inbox.
Implementing BIMI
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Design and Host the SVG Logo:
- Create an SVG version of your brand logo that meets BIMI requirements (square aspect ratio, optimized for clarity).
- Host the logo at a publicly accessible URL, such as
https://yourdomain.com/bimi/logo.svg.
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Create the BIMI DNS TXT Record:
- Publish a TXT record at
default._bimi.yourdomain.comwith the following content:
- Publish a TXT record at
Conclusion
Implementing these protocols ensures that your emails are authenticated, secure, and trusted by recipients. Start with SPF, DKIM, and DMARC, and consider adopting MTA-STS, TLS-RPT, and BIMI for a comprehensive email security strategy.
