Email Requirements Explained

To ensure security, reliable communication, and platform integrity, Directory9 requires all users to register with a valid email address. This email address must include proper DNS records for:

DNS MX (Mail Exchanger) Records

MX records tell the internet which mail server accepts incoming email for your domain. Without a valid MX, many systems (including Directory9) treat the address as unreachable.

What this does: Routes inbound email to the right server. An MX record must point to a hostname (that has an A/AAAA record), not directly to an IP address.

Key rules:

MX ➜ hostname only (e.g., mail.yourdomain.com), not an IP.
No CNAME on the MX target — use an A record (IPv4) or AAAA record (IPv6) on the hostname.
Use a priority number (lower = higher priority).
Typical TTL: 3600 seconds (1 hour).

Example MX Records (self-hosted mail):

Name: yourdomain.com
Type: MX
Priority: 10
Value: mail.yourdomain.com.

Example MX (Google Workspace):

Priority 1   ASPMX.L.GOOGLE.COM.
Priority 5   ALT1.ASPMX.L.GOOGLE.COM.
Priority 5   ALT2.ASPMX.L.GOOGLE.COM.
Priority 10  ALT3.ASPMX.L.GOOGLE.COM.
Priority 10  ALT4.ASPMX.L.GOOGLE.COM.

Example MX (Microsoft 365):

Priority 0   yourdomain-com.mail.protection.outlook.com.

Common mistakes to avoid:

Pointing MX directly to an IP (must be a hostname with an A/AAAA record).
Using a CNAME as the MX target.
Leaving the domain without any MX records (many providers reject such addresses).

How to Test Your MX

After adding/updating records, allow DNS to propagate, then verify:

You can also use the tools below (already listed on this page): DNS Checker, MXToolbox, Mail-Tester, or dmarcian.

SPF (Sender Policy Framework)

Confirms which mail servers are allowed to send email on behalf of your domain.

What this does: Helps prevent others from spoofing your domain by specifying which IP addresses or servers are allowed to send email from it.

Example SPF Records:

If your server sends directly:

v=spf1 +a +mx ip4:000.000.000.000 ~all

If you send through your server and also use Google as a relay:

v=spf1 +a +mx ip4:000.000.000.000 include:_spf.google.com ~all

If you only use Google (Gmail/Google Workspace) for sending email:

v=spf1 include:_spf.google.com ~all

DKIM (DomainKeys Identified Mail)

Adds a digital signature to verify that the message wasn't altered during transmission.

What this does: Ensures your email content hasn’t been tampered with and proves that the email was sent from your domain.

Example DKIM Record:

Name: default._domainkey.yourdomain.com
Value: v=DKIM1; k=rsa; p=MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAnX8...

DMARC (Domain-based Message Authentication, Reporting & Conformance)

Tells receiving servers how to handle emails that fail SPF or DKIM checks.

What this does: Combines SPF and DKIM results and defines a policy (none, quarantine, or reject) for handling failed messages. Also enables reporting to help you monitor abuse.

Example DMARC Record:

v=DMARC1; p=quarantine; rua=mailto:[email protected]

How to Check Your Email DNS Records

Use one of these free tools to verify your email setup:

Why This Matters

Invalid or misconfigured email addresses can cause bounce-backs, damage Directory9’s email server reputation, and prevent important messages from reaching you and other users.

To maintain platform security and reliability, accounts using non-compliant email addresses may be suspended or removed.