What is the dig tool useful for in email marketing?
Michael Ko
Co-founder & CEO, Suped
Published 25 Apr 2025
Updated 16 Aug 2025
9 min read
When you send an email, it's not just a simple point-and-click operation. Behind the scenes, a complex system of DNS (Domain Name System) records works to ensure your message reaches its intended recipient. These records are crucial for everything from verifying your sender identity to routing your emails correctly. If any of these DNS records are misconfigured or missing, your emails might not be delivered, ending up in spam folders, or being rejected outright.
This is where the dig tool comes into play. Short for Domain Information Groper, dig is a powerful command-line utility used for querying DNS name servers. While it might sound technical and intimidating at first, understanding its basic functions can provide invaluable insights into your email infrastructure and help diagnose deliverability issues that might otherwise remain hidden.
In email marketing, deliverability is paramount. It doesn't matter how compelling your content is if your emails never make it to the inbox. By using dig, you can proactively check your domain's DNS records, identify potential problems, and ensure your email authentication mechanisms, like SPF, DKIM, and DMARC, are correctly configured. This foundational understanding is key to maintaining a strong sender reputation and achieving higher inbox placement rates.
Understanding DNS and email deliverability
At its core, dig allows you to request specific information from DNS servers. Think of DNS as the internet's phonebook, translating human-readable domain names (like yourdomain.com) into machine-readable IP addresses. For email, this translation involves several record types that guide how mail servers interact with your domain.
The most fundamental record for email is the MX (Mail Exchange) record. This record tells other mail servers where to send emails for your domain. If your MX records are incorrect, emails simply won't reach your recipients, or you won't receive incoming mail. You can use dig to quickly verify your domain's MX records, ensuring they point to the correct mail servers.
Beyond MX records, dig is also essential for checking A records (which map a domain to an IP address) and TXT records (which store text information, often used for email authentication). By routinely checking these with dig, you can catch misconfigurations early, preventing potential deliverability headaches. For example, if your A record is not correctly pointing to your sending IP, it could lead to mail servers distrusting your domain. The Linux dig command tutorial provides more detail on various query types.
Diagnosing email authentication issues
Email authentication protocols like SPF, DKIM, and DMARC are fundamental for preventing spoofing and phishing, and ultimately for ensuring your emails land in the inbox. These protocols rely heavily on correctly configured DNS TXT records. Dig is the perfect tool for verifying that these critical records are published correctly and are accessible to receiving mail servers. Without proper authentication, even legitimate emails can be flagged as spam.
To check your SPF (Sender Policy Framework) record, you'd query for a TXT record. SPF specifies which mail servers are authorized to send email on behalf of your domain. A misconfigured SPF record can lead to soft failures or hard rejections, impacting your deliverability. Similarly, for DKIM (DomainKeys Identified Mail), you'll query a TXT record for a specific selector. DKIM adds a digital signature to your emails, allowing recipients to verify that the email hasn't been tampered with in transit. Checking SPF records with dig is a common use case.
DMARC (Domain-based Message Authentication, Reporting, and Conformance) builds upon SPF and DKIM, telling receiving servers how to handle emails that fail authentication. It also provides valuable reports on your email traffic. Using dig to check your DMARC record is crucial for ensuring your policies are correctly implemented. I find it incredibly useful to quickly confirm if these records are present and properly formatted, which is often the first step in troubleshooting any email authentication failures. You can learn more about DMARC, SPF, and DKIM in our detailed guides.
Example dig commands for email authentication recordsbash
One of the most frustrating aspects of email marketing is when your perfectly crafted messages end up in the spam folder or get blocked entirely. Dig can be a frontline diagnostic tool for these scenarios. If your emails aren't reaching their destination, you can use dig to check various DNS records related to your domain and IP address. This can help pinpoint if the issue lies with your DNS setup or elsewhere. For example, checking your domain's status on blacklists is a common diagnostic step.
A common deliverability hurdle is being listed on an email blacklist (or blocklist). While dig can't directly tell you if you're on a blacklist, it can help you retrieve your IP address. Once you have your IP, you can use a dedicated blacklist checker to see if it's listed. Understanding how email blacklists work is essential for proactive deliverability management. Additionally, a reverse DNS lookup using dig (querying for PTR records) can verify if your IP address correctly resolves back to your domain, a factor many mail servers consider for trustworthiness.
While manual dig queries are powerful, they are often just one step in a comprehensive deliverability strategy. Tools that offer all-round email deliverability tracking can automate many of these checks and provide a more holistic view. However, knowing how to use dig empowers you to perform quick, on-the-spot diagnoses when issues arise, offering immediate clarity before escalating to more advanced tools. For example, you can troubleshoot why your emails are going to spam.
Manual dig utility
Granular control: Allows for precise queries of specific DNS record types.
Direct output: Provides raw DNS responses, useful for deep debugging.
No cost: Freely available on most Unix-like operating systems.
Learning curve: Requires familiarity with command-line interfaces.
Automated deliverability tools
Comprehensive analysis: Checks multiple factors beyond DNS, like content and reputation.
User-friendly: Often provides dashboards and actionable recommendations.
Proactive monitoring: Can alert you to issues as they arise.
Cost involved: Typically a paid service with varying pricing tiers.
Beyond basic queries
While checking individual record types is valuable, dig offers more advanced functionalities that can provide deeper insights into your DNS resolution path. The +trace option, for instance, allows you to trace the delegation path from the root name servers, through the top-level domain (TLD) servers, down to the authoritative name servers for your domain. This can be immensely helpful in identifying where a DNS lookup might be failing or if there are any unexpected redirects.
Understanding DNS propagation is another area where dig shines. When you make changes to your DNS records, it takes time for these changes to update across the internet's DNS servers. This is known as propagation. Using dig with a specific nameserver (e.g., @8.8.8.8 for Google DNS) allows you to query specific DNS servers to see if your changes have propagated to them, providing real-time insight into the deployment of your DNS updates.
Query Type
Description
Email Marketing Utility
MX
Mail Exchange records for receiving email.
Ensuring emails are routed to correct mail servers.
TXT
Text records, used for SPF, DKIM, DMARC.
Verifying proper email authentication setup.
A
Maps a domain to an IPv4 address.
Confirming your domain resolves to the correct IP.
PTR
Reverse DNS, maps IP to domain (e.g. for IP dig -x 1.2.3.4).
Ensuring IP has a valid hostname, improving sender reputation.
Complementing dig with other tools
Best practices for using dig
Verify new DNS records immediately: After making any changes to SPF, DKIM, or DMARC, use dig to confirm they are published correctly before expecting full functionality.
Use specific query types: Don't just run a general dig command, specify MX, TXT, or A records to get relevant results for email troubleshooting.
Check from different resolvers: Query different public DNS servers (e.g., @8.8.8.8, @1.1.1.1) to confirm global propagation of your DNS changes.
Dig is a command-line tool, and while it provides direct access to DNS information, it may not be intuitive for everyone. Thankfully, there are online GUI versions, such as Google's Dig tool, that offer a user-friendly interface for the same powerful queries. These web-based tools are excellent for quick checks without needing to access a terminal.
For ongoing monitoring and more complex analysis, specialized DMARC report analysis and email deliverability monitoring tools can be invaluable. These tools often integrate dig-like functionalities into a broader suite, offering automation, historical data, and more actionable insights into your email performance. They can help you understand nuances like SPF TempError or DKIM body hash mismatches, which can be tricky to diagnose with dig alone.
Views from the trenches
Best practices
Always verify any DNS changes instantly with dig before assuming they've propagated, as this prevents unexpected deliverability issues.
Integrate dig commands into your pre-send checklist to ensure email authentication records are correctly published before large campaigns.
Use dig to perform reverse DNS lookups on your sending IPs to confirm proper PTR records are in place, enhancing trust with recipients.
Cross-reference dig output with your email service provider's DNS requirements to ensure all necessary records are configured.
Common pitfalls
Forgetting to check the TXT records for SPF and DMARC specifically, leading to authentication failures that impact inbox placement.
Misinterpreting dig output, especially for complex DNS configurations like multiple MX records or CNAME chains.
Relying solely on dig for comprehensive deliverability monitoring without combining it with other specialized tools.
Not understanding DNS propagation delays, expecting immediate results after updating records, which can cause confusion.
Expert tips
Use the `+short` option with dig for cleaner output when you only need the answer, especially for automated scripts.
Combine dig with a specific nameserver (e.g., `dig @ns1.yourprovider.com yourdomain.com`) to troubleshoot issues with a particular DNS provider.
Familiarize yourself with common DNS error codes in dig's output, such as NXDOMAIN or SERVFAIL, to quickly identify root causes.
Consider setting up automated scripts using dig to periodically check critical DNS records and alert you to any unexpected changes.
Marketer view
Marketer from Email Geeks says they found Google's online dig tool to be very interesting for quick lookups.
2022-06-07 - Email Geeks
Marketer view
Marketer from Email Geeks says that the dig tool is very useful.
2022-06-07 - Email Geeks
The indispensable DNS diagnostic tool
The dig tool is an indispensable utility for anyone serious about email marketing and deliverability. While it might seem like a niche technical tool, its ability to quickly and accurately query DNS records makes it a cornerstone for diagnosing and preventing common email sending issues. From verifying your basic mail routing via MX records to confirming the intricate details of your SPF, DKIM, and DMARC configurations, dig provides the raw data you need to ensure your email infrastructure is sound.
Mastering dig, even at a basic level, empowers you to take control of your email deliverability. It allows you to confidently troubleshoot problems, verify changes, and understand the fundamental workings of your email sending domain. Coupled with automated monitoring solutions, dig becomes a powerful component in any email marketer's toolkit, helping to boost your sender reputation and consistently land your messages in the inbox.
Google DNS) allows you to query specific DNS servers to see if your changes have propagated to them, providing real-time insight into the deployment of your DNS updates.
