In Google Workspace (Gmail) Admin settings, address lists are commonly used to control allowlisting, blocklisting, and authentication requirements for inbound and outbound email.
A frequent point of confusion for administrators is which address format is correct—whether to use:
example.com
@example.com
user@example.com
Using the wrong format can result in duplicate rules, ineffective filtering, or false security assumptions.
This knowledge base article explains the correct domain style, how Gmail processes address lists internally, and how to configure them properly for security, clarity, and long-term maintenance.
An address list in Gmail Admin Console is a reusable object that contains:
Email addresses
Domains
IP addresses (in some policies)
These lists are referenced by:
Gmail compliance rules
Spam, phishing, and spoofing controls
Authentication-required policies
Allow / block sender configurations
| Format | Meaning | Scope |
|---|---|---|
example.com | Entire domain | All users under the domain |
user@example.com | Single mailbox | Only one sender |
@example.com | Domain with prefix | Functionally redundant |
Subdomain (mail.example.com) | Subdomain only | Limited scope |
When you add:
example.com
Gmail automatically treats it as:
This includes:
Adding @example.com does not provide additional coverage and is treated as duplicate logic.
Use domain-only entries to allow email from partners, banks, vendors, or government portals.
Require SPF/DKIM/DMARC authentication for known domains to prevent spoofed emails.
Prevent all incoming mail from unwanted or malicious domains.
When only one mailbox should be trusted:
Sign in to Google Admin Console
Navigate to:
Apps → Google Workspace → Gmail
Open Spam, phishing and malware
Select Address lists
Click Edit address list or Add address list
✅ Correct
❌ Avoid
❌ Avoid unless needed
Enable Authentication required (received mail only) if:
The domain supports SPF/DKIM/DMARC
You want to prevent spoofing
Click Save
Ensure the address list is referenced in the intended Gmail rule
Although Gmail Admin Console is GUI-based, conceptually the rule behaves as:
For single sender:
Problem
Fix
Remove @example.com
Keep only example.com
Cause
Authentication not enforced
Fix
Enable Authentication required
Ensure SPF/DKIM/DMARC are configured on sender domain
Cause
Sender uses a different subdomain
Fix
Add additional domain:
Cause
Using domain instead of specific sender
Fix
Replace:
with:
Domain allowlisting bypasses some spam protections
Never allowlist unknown or public email providers
Always pair allowlisting with authentication checks
Review address lists quarterly
Remove legacy or unused domains
✅ Use domain-only format (example.com)
✅ Avoid @domain.com entries
✅ Use single email only when strictly required
✅ Enforce SPF/DKIM/DMARC wherever possible
✅ Keep address lists minimal and documented
❌ Do not mix domain and @domain entries
❌ Do not allowlist free/public email domains
For Google Workspace Gmail address lists, the correct and recommended format is the plain domain name (e.g., example.com).
Using @example.com is redundant, adds confusion, and provides no additional security benefit.
A clean, domain-only configuration ensures:
Predictable behavior
Strong anti-spoofing protection
Easier long-term administration
Compliance with Google’s internal mail-processing logic
Correct formatting is a small change with a significant impact on email security and reliability.
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