Summary
Resolving email deliverability issues with .mil email addresses presents unique challenges due to the specific security protocols and operational mandates of military domains. Unlike commercial internet service providers (ISPs), Department of Defense (DoD) networks operate under stringent rules, often unrelated to typical spam filtering. This means traditional methods for appealing blocklists or improving sender reputation may not apply.
Key findings
- .mil domains: These are distinct from commercial ISPs, with blocks often stemming from security policies rather than spam detection.
- DNS issues: Some .mil domains may not be publicly accessible via DNS, being restricted to internal networks.
- Plain text preference: Historically, .mil addresses have preferred or exclusively accepted plain text emails, rejecting HTML content.
- Limited recourse: Appealing deliverability decisions to military postmasters is typically ineffective, as their mandates prioritize security and official communication over commercial or general correspondence. This is distinct from how you might contact mailbox providers for other domains.
Key considerations
- Purpose of email: Understand that .mil addresses are primarily for official military communications, not for general commercial or personal content, even if recipients have opted in. This aligns with email deliverability best practices regarding audience and content.
- Recipient education: Advise individuals with .mil addresses to use a personal email for non-official correspondence. This can be integrated into signup forms or communication preferences.
- Content format: If you must send to .mil, prioritize plain text. Avoid HTML, images, and complex formatting to increase deliverability chances, as outlined in guides about best practices for government domains.
- Alternative addresses: Consider suppressing .mil addresses from your mailing lists if deliverability consistently fails and encourage alternative non-.mil contact points.
What email marketers say
Email marketers often encounter significant hurdles when trying to send messages to .mil email addresses, even with fully opt-in lists. Their experiences highlight the unique and often unyielding nature of military email systems, which operate under different rules than standard commercial or organizational email providers.
Key opinions
- Specific cases: Marketers find that .mil domains are a very special case, where blocks are often not related to typical spam complaints or content issues.
- DNS visibility: Some .mil domains might be pulled from public DNS, making them only reachable from specific, internal networks, adding to delivery complexity.
- Content limitations: Past experiences suggest that .mil recipients might only accept plain text emails, leading to rejections for HTML-formatted messages.
- Operational focus: The Department of Defense (DoD) email space is distinct from commercial ISP space, with different rules that do not prioritize facilitating non-military usage.
Key considerations
- Recipient alternative: It may be more effective to ask recipients to provide a non-.mil email address for general communications, as .mil addresses are intended for official purposes.
- Signup form adjustments: Implement a special mention on signup forms encouraging military personnel to use their personal email addresses. This helps in proactively addressing deliverability challenges and maintaining a healthy sender reputation, which is crucial for overall deliverability.
- Suppression strategy: Consider a policy to suppress all .mil emails from marketing or non-essential communications if delivery consistently fails, minimizing impact on your overall sender reputation.
- Contacting postmasters: Direct contact with .mil postmasters might be possible in some cases, but be prepared for limited assistance due to their specific operational priorities.
Marketer view
An email marketer from Email Geeks asked about contacting postmasters or resources to lift blocks on .mil email addresses for an opt-in client sending geopolitical updates. They were looking for specific channels to address deliverability issues unique to these domains.
Marketer view
An email marketer from Email Geeks stated that they would consider including a special mention in their signup form to advise military personnel to use their personal email addresses moving forward. This proactive approach aims to avoid deliverability challenges with .mil domains.
What the experts say
Email deliverability experts highlight that .mil domains are exceptionally unique environments within the email ecosystem. Their operational mandates prioritize national security and official communications, leading to filtering rules and network configurations that differ significantly from commercial email providers. This often means that standard deliverability troubleshooting steps are less effective.
Key opinions
- Unique environment: .mil is a very special case where blocks are often unrelated to typical spam issues. It's Department of Defense (DoD) space, not commercial ISP space.
- Network restrictions: Many .mil domains have been removed from public DNS and are only reachable from specific internal networks for security reasons.
- Content format strictness: Experts have observed that .mil systems might only accept plain text emails, rejecting HTML content, which can cause unexpected delivery failures.
- No appeal process: Unlike commercial providers, military domains typically do not offer an appeal process for blocked emails, as their decisions are driven by strict operational requirements rather than commercial considerations. This differs from how you might resolve Outlook email deliverability issues.
Key considerations
- Inform recipients: It's advisable to encourage military personnel to use non-.mil addresses for general communications to ensure reliable delivery.
- Content adaptation: If sending to .mil is unavoidable, ensure content is strictly plain text and minimalistic to maximize delivery chances. Avoid anything that could trigger security filters, such as complex HTML or tracking pixels, as these domains are not designed for marketing. Also, consider the impact of RFC compliance errors.
- Sender reputation: Persistent attempts to send to blocked or unresponsive .mil addresses can negatively impact your sender reputation, including potentially landing on a general blacklist or blocklist. Proactive reputation management is key.
- Suppression: In cases of persistent blocks, consider suppressing .mil addresses from your mailing lists to avoid high bounce rates and protect overall deliverability. This also applies to internal blocklists.
Expert view
An email expert from Email Geeks (U3HV54286) stated that .mil domains are very specific and that deliverability blocks are often not due to typical spam issues. Their operational environment differs significantly from commercial internet service providers.
Expert view
An email expert from Email Geeks (U3HV54286) observed that many .mil domains have been withdrawn from public DNS and are now only reachable via specific, internal networks. This greatly complicates external email delivery.
What the documentation says
Official documentation and military network guidelines often emphasize security, operational necessity, and strict adherence to protocols for all incoming and outgoing electronic communications. These guidelines typically dictate conservative approaches to email content, attachments, and external connectivity, impacting how non-official emails are handled.
Key findings
- Security priority: Military networks prioritize cybersecurity and mission-critical communications, making them inherently more restrictive than commercial email services.
- Network isolation: Some segments of .mil networks are designed for internal use, limiting direct external connectivity and filtering non-essential traffic.
- Content restrictions: Documentation often recommends or mandates plain text for communications, and complex HTML, embedded media, or numerous external links are typically discouraged or blocked for security reasons.
- Purpose-driven: .mil email systems are primarily for official business. Any email perceived as non-official, even if subscribed, may be filtered, blocked, or sent to a blocklist without notification.
Key considerations
- Adherence to standards: While adhering to email authentication standards like SPF, DKIM, and DMARC is crucial for any domain, military networks may have additional, internal checks. Ensure your DMARC, SPF, and DKIM records are correctly configured.
- Content simplicity: Prioritize simple, plain text content. Avoid all unnecessary formatting, images, and links. This aligns with many RFCs which define basic email structures.
- Domain reputation: Even if a .mil domain doesn't publicly list on a blacklist, its internal filtering systems act as a powerful blocklist. Consistent attempts to send non-compliant emails can still impact your overall domain reputation.
- Alternative communication: Documentation often implies that official channels or alternative communication methods are preferred for sensitive or non-standard interactions.
Technical article
The DoD Joint Technical Architecture states that all information systems connected to DoD networks must adhere to stringent security controls, which often involve advanced email filtering and content inspection. This implies a highly controlled environment for all incoming mail.
Technical article
RFC 2046, which defines the MIME (Multipurpose Internet Mail Extensions) media types, notes that while HTML is a valid content type, some email environments, particularly those with heightened security, may default to or strictly enforce plain text rendering for security and simplicity, impacting HTML email delivery.
Related resources
3 resources
Related pages
Best practices for email deliverability to government and .mil accounts.
How to contact mailbox providers for email deliverability issues?
What steps can I take to resolve email deliverability issues and improve my sender reputation?
Why your emails are going to spam in 2024 and how to fix it
An in-depth guide to email blocklists
A simple guide to DMARC, SPF, and DKIM
How to troubleshoot email delivery issues related to RFC compliance errors?
How do email experts troubleshoot customer deliverability issues?
