Email Deliverability Report
Updated Apr 1, 2026
Costco
Domain: costco.com
Costco uses DMARC for membership and promotional communications.
Overall Email Deliverability Grade
Good email deliverability practices
Email Service Provider
In-house
IP Type
shared IP
Blacklist Status
Clean
Industry
ecommerce
Email Authentication Setup
SPF
Configuredv=spf1 include:costco.com ~all
DKIM
ConfiguredDKIM for costco.com
DMARC
Configuredp=quarantine; rua=mailto:dmarc@costco.com
Policy: quarantine
DMARC Policy: QUARANTINE
Moderate enforcement. Emails failing DMARC authentication are marked as suspicious and often placed in spam folders rather than rejected outright.
BIMI & Brand Trust Signals
BIMI Record
Not currently using BIMI. This feature displays your brand logo next to emails in Gmail and other providers that support it.
VMC Verification
VMC verification not currently in use for additional brand trust.
Sending Infrastructure
Email Service Provider
In-house
Operates their own email sending infrastructure for maximum control and deliverability.
IP Configuration
shared IP Address
Shares IP infrastructure. Reputation depends on shared pool behavior, but simplifies management.
Blacklist Status
Not Listed on Major Blacklists
Costco maintains a clean reputation across major DNS-based blacklist providers. Emails are not being blocked based on IP or domain reputation.
Key Takeaways
Costco takes email deliverability seriously with a Grade B authentication setup.
DMARC policy set to quarantine shows a proactive approach to brand protection.
Using shared sending infrastructure shows a preference for simplified email operations.
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