Military Email Setup Guide: CAC Access for Outlook, OWA, and Mobile

Accessing your military email from home or on the go requires proper CAC configuration. Whether you’re using Outlook desktop, Outlook Web Access (OWA), or your mobile device, this guide covers everything you need to know about setting up secure email access.

We’ll walk through the complete setup process for each platform, including troubleshooting tips for common issues.

Understanding Military Email Systems

The Department of Defense operates several email systems, each requiring CAC authentication:

Army 365 / Navy 365 / Air Force 365

Most branches now use Microsoft 365 Government (M365) for email. Access points include:

• Army: webmail.apps.mil
• Navy/Marines: webmail.apps.mil
• Air Force: webmail.apps.mil

Legacy DEE (Defense Enterprise Email)

Some organizations still use the older DEE system accessible at mail.mil.

OWA (Outlook Web Access)

Browser-based email access available through your service’s portal.

Prerequisites for Email Setup

Before configuring email access, ensure you have:

• Working CAC reader (see our setup guide)
• Current DoD root certificates installed
• Valid CAC with non-expired certificates
• Your CAC PIN
• Active email account (check with your unit IT)

Outlook Web Access (OWA) Setup

OWA is the fastest way to access your email without installing additional software.

Step 1: Configure Your Browser

For best results, use Microsoft Edge or Google Chrome:

1. Ensure DoD root certificates are installed
2. Close all browser windows
3. Insert your CAC
4. Open your browser

Step 2: Navigate to Webmail

1. Go to webmail.apps.mil
2. When prompted, select your email certificate (usually contains “EMAIL” in the name)
3. Enter your CAC PIN
4. You should reach your inbox

Browser-Specific Tips

Microsoft Edge:

• Generally works best with DoD sites
• Uses Windows certificate store automatically
• Clear cache if experiencing issues

Google Chrome:

• Also uses Windows certificate store
• May require enabling hardware security keys in settings

Firefox:

• Requires separate certificate configuration
• Go to Settings > Privacy & Security > Security Devices
• Load the appropriate security module

Microsoft Outlook Desktop Setup

For a full-featured email experience, configure Outlook with your military account.

Outlook with Microsoft 365

1. Open Outlook
2. Go to File > Add Account
3. Enter your @mail.mil or @us.army.mil address
4. Click Connect
5. When prompted, select your CAC certificate
6. Enter your PIN
7. Allow Outlook to complete configuration

Manual Configuration (If Auto-Discovery Fails)

1. Go to File > Account Settings > Account Settings
2. Click New
3. Select “Manual setup or additional server types”
4. Choose “Microsoft Exchange or Office 365”
5. Enter server: outlook.office365.com
6. Check “Require logon using Secure Password Authentication”
7. Complete setup with CAC authentication

Configure S/MIME for Signed and Encrypted Email

1. Go to File > Options > Trust Center > Trust Center Settings
2. Select Email Security
3. Click Settings under Encrypted Email
4. Select your signing and encryption certificates from your CAC
5. Click OK to save

Watch: Email Certificate Selection

Understanding which certificate to use is critical for email access:

Mobile Email Setup (iPhone and Android)

Accessing military email on mobile devices requires specialized hardware and apps.

Required Equipment

• Mobile CAC Reader: Bluetooth or Lightning/USB-C compatible
• CAC-Enabled App: Smart Card Utility, PKard Reader, or similar
• DoD Certificates: Must be installed on device

iPhone/iPad Setup

1. Download “Smart Card Utility” from App Store
2. Connect your mobile CAC reader
3. Insert your CAC into the reader
4. Open Smart Card Utility and follow prompts
5. Install DoD certificates when prompted
6. Open Safari and navigate to webmail.apps.mil
7. Authenticate with your CAC

Android Setup

1. Download CAC-enabled browser app
2. Connect USB-C or Bluetooth CAC reader
3. Install DoD certificates
4. Access webmail through the app

Alternative: Outlook Mobile with Intune

If your organization uses Microsoft Intune for mobile device management:

1. Download Microsoft Outlook from app store
2. Download Microsoft Authenticator
3. Enroll your device in Intune (contact your IT department)
4. Configure derived credentials for CAC authentication
5. Add your military email account in Outlook

Troubleshooting Common Email Issues

“Cannot Connect to Server”

• Verify internet connection
• Check if DoD sites are accessible (try another CAC-enabled site)
• Ensure VPN is connected if required
• Try a different browser

“Certificate Error” or “No Valid Certificates”

• Check CAC certificate expiration dates
• Reinstall DoD root certificates
• Clear browser cache and cookies
• Remove and reinsert CAC

Outlook Keeps Asking for Credentials

This common issue has several solutions:

1. Clear stored credentials in Windows Credential Manager
2. Remove and re-add the email account in Outlook
3. Ensure “Remember credentials” is checked
4. Disable password prompts in Outlook security settings
5. Check that your certificate isn’t cached incorrectly

“Your Mailbox Has Been Moved”

• Your account may have migrated to M365
• Update Outlook to use the new server
• Contact your IT help desk for migration assistance

S/MIME Signature Errors

• Ensure signing certificate is selected in Trust Center
• Verify certificate hasn’t expired
• Recipient may need your public key to verify signature

Email Security Best Practices

• Always sign sensitive emails using your CAC signature certificate
• Encrypt emails containing PII or sensitive information
• Never forward encrypted emails to personal accounts
• Log out completely when using shared computers
• Remove CAC after accessing email
• Don’t save passwords on shared or public computers

Email Access Methods Comparison

Summary

Setting up military email access with your CAC enables secure communication from virtually anywhere. The key steps are ensuring your CAC reader is properly configured, DoD certificates are installed, and your browser or email client is set up correctly.

For most users, OWA provides the quickest path to email access without complex configuration. Power users who need offline access and advanced features should configure Outlook desktop with S/MIME support.

If you’re experiencing persistent issues, check your certificate expiration dates and ensure you’re selecting the correct certificate (EMAIL, not ID or SIGNATURE) when prompted.