Emails from Coinbase will always have the coinbase.com domain name at the end of them. For example emails from firstname.lastname@example.org, email@example.com, firstname.lastname@example.org, and any other email from the @coinbase.com domain can be trusted
We also send emails from Coinbase sub-domains. For example a message from email@example.com are valid. Note that the email address ends in .coinbase.com.
Regardless of sub-domain, we cryptographically sign all of our emails using DKIM and protect our domain against unsigned email with DMARC.
To verify the legitimacy of other channels, refer to these pages for social media and phone support.