Gmail can clearly mark authenticated messages from certain senders. Since all mail from these senders is sent with authentication, messages that appear to come from these senders but lack the mark can be regarded as fraudulent.
In Gmail, the indicator is a golden key, and the senders currently are eBay and PayPal.
Identify Authenticated Senders and Avoid Phishing in Gmail
To have Gmail show a key icon next to messages that have been authenticated to come from the sender that appears in the From: line:
- Follow the Settings link in Gmail.
- Go to the Labs tab.
- Make sure Enable is selected for Authentication icon for verified senders.
- Click Save Changes.