The question of whether it's safe to email DNS records is one that comes up fairly often, especially when you're dealing with new integrations or handing off technical details to a third party. On the surface, it might seem like a security risk, given how critical DNS records are to your online presence, including your email operations.
However, the reality is a bit more nuanced than a simple yes or no. Most DNS records are designed to be publicly accessible, as they are the roadmap that directs internet traffic to your domain. This public nature is fundamental to how the internet functions, allowing mail servers to find where to send your emails and web browsers to locate your website. Let's dive into the specifics.
Understanding DNS records for email
DNS records are the backbone of your domain's online identity, including how your email works. For email, several specific types of DNS records are crucial for ensuring messages are delivered correctly and securely. These records help other mail servers verify that emails originating from your domain are legitimate, preventing spam and phishing attacks.
The MX record (Mail Exchange) is perhaps the most fundamental, directing incoming emails to the correct mail servers. Without a properly configured MX record, your domain cannot receive emails. While some older systems might accept mail without an MX record, it is generally considered bad practice to send email from a domain without one, impacting deliverability.
Beyond basic routing, authentication records like SPF, DKIM, and DMARC are essential for verifying sender identity. SPF (Sender Policy Framework) specifies which mail servers are authorized to send emails on behalf of your domain. DKIM (DomainKeys Identified Mail) adds a digital signature to your emails, allowing recipients to verify that the email was sent by the domain owner and hasn't been tampered with. DMARC (Domain-based Message Authentication, Reporting, and Conformance) builds on SPF and DKIM, telling recipient servers how to handle emails that fail authentication.
Security: These records help prevent malicious actors from spoofing your domain for phishing or spam campaigns.
Reputation: Maintaining accurate and complete DNS records contributes positively to your domain's sender reputation with mailbox providers.
Public availability versus sensitive data
A common misconception is that DNS records are secret or private information. In reality, the entire Domain Name System is built on public accessibility. When a mail server (or any internet service) needs to find information about your domain, it performs a DNS lookup, which is publicly available. Anyone can query DNS records for any domain using widely available tools.
This means that emailing your SPF, DKIM, or DMARC records typically poses no additional security risk beyond what is already inherent in the internet's design. If a malicious actor wants to find your domain's email authentication records, they don't need to hack into your email. They can simply perform a public lookup, just like legitimate mail servers do every day.
The concern often stems from the idea that if someone has your DNS records, they could use your domain for their own purposes. However, merely possessing the records is not enough. To make any changes or send emails on your behalf, an attacker would need access to your DNS hosting provider's account credentials or your email sending platform.
DNS record accessibility
Publicly discoverable: Most DNS records are designed to be retrieved by anyone, anytime.
No direct risk: Knowing your DNS records does not automatically grant control over your domain.
Sensitive information
Hosting credentials: Usernames and passwords for your DNS provider should never be shared via email.
DKIM private keys: These are cryptographic keys that must remain secret.
Identifying sensitive DNS components
While most DNS records are safe to email, there's one critical exception, your DKIM private key. DKIM uses a pair of cryptographic keys: a public key, which is published in your DNS (often as a TXT record), and a private key, which is kept secret by your email sending service or server. The private key is used to sign your outgoing emails, and the public key allows recipients to verify that signature.
Exposing your DKIM private key would be a serious security breach, as it would allow unauthorized parties to send emails appearing to come from your domain, passing DKIM authentication checks. This could lead to widespread spoofing, phishing, and severe damage to your brand reputation and email deliverability. If you encounter errors like DKIM temperror, it usually points to configuration issues, not key exposure.
Other records, such as MX, SPF, or DMARC records (which are typically TXT records), are inherently public. Their values are needed by other servers to correctly process your emails. Sharing these via email for setup or troubleshooting purposes is generally safe, as long as you are only sharing the record values themselves, not the credentials to modify them.
HIGH risk. Never email this. It should remain secret.
Best practices for sharing DNS information
When you need to share DNS records, it's generally safe to email the actual record values, such as the full TXT string for SPF or DMARC, or the hostname and value for an MX record. These are the pieces of information that mail servers (and anyone performing a DNS lookup) would naturally discover.
What you should never email are your DNS hosting credentials (usernames, passwords) or any private keys, specifically your DKIM private key. These are the keys to the kingdom. If someone gains access to these, they can modify your DNS records, hijack your domain, or send emails pretending to be you, regardless of whether they saw a public DNS record in an email.
When setting up or modifying DNS records, it is crucial to use secure methods for any sensitive information. Use a password manager for credentials, and securely transfer private keys only if absolutely necessary and through encrypted channels. For everything else, emailing the actual record values is typically fine.
Securely handling DNS information
Share record values: It's safe to send the plain text of MX, SPF, DKIM public, and DMARC records.
Never email credentials: Access details for your DNS provider should be shared via secure means like a password manager.
Protect private keys: The DKIM private key must remain secret and never be transmitted via insecure methods like email.
In summary, emailing most DNS records, such as your MX, SPF, DKIM public key, and DMARC records, is generally safe. These records are inherently public information necessary for the proper functioning of your domain's email. The primary security concern lies not with the records themselves, but with how you manage access to your DNS hosting account and sensitive cryptographic keys.
Always exercise caution with your DNS hosting credentials and private cryptographic keys like the DKIM private key. These should never be emailed. By understanding the distinction between publicly available DNS records and sensitive access credentials, you can safely manage your domain's configuration without undue risk.
Views from the trenches
Best practices
Use secure, encrypted channels for transmitting any sensitive data, especially DNS hosting credentials and private cryptographic keys.
Regularly review your DNS records to ensure they are accurate and don't contain any unauthorized entries that could indicate a compromise.
Implement DMARC with a strong policy to protect against domain spoofing, even if your records become known to malicious actors.
Common pitfalls
Sending DNS hosting account usernames and passwords via unencrypted email, which provides direct access to modify your records.
Not understanding the difference between public DNS record values and private keys or credentials.
Assuming that because DNS records are public, there is no need for any security precautions when sharing them.
Expert tips
Always verify the recipient's identity before sharing any DNS-related information, even if it's publicly available.
Consider using a dedicated project management tool or secure file sharing service for technical configurations, rather than email.
Educate your team on what constitutes sensitive DNS information versus publicly shareable data to prevent accidental exposure.
Expert view
Expert from Email Geeks says: DNS records are publicly available and must be published for your domain to function correctly.
Feb 12, 2024 - Email Geeks
Expert view
Expert from Email Geeks says: Sending DNS records in clear text via email might seem risky, but malicious actors can easily obtain this information by reviewing email headers or public DNS lookups.
Most DNS records are designed to be retrieved by anyone, anytime.
