Spam and suspicious emails
Gmail automatically helps identify spam and suspicious emails by detecting viruses, finding patterns across messages, and learning from what Gmail users like you commonly mark as spam or phishing.
If you click your Spam label and open one of the messages, you'll see a warning label at the top with a brief explanation about why that particular message was placed in Spam. If we think something is suspicious, we’ll mark the message with a warning label in your inbox for you.
Use this information to protect yourself from potentially dangerous or fraudulent messages and to better understand why a message was or wasn't marked as spam.
Here are some of the explanations that you might see: