Important: To prevent emails from being blocked or sent to spam, you can find info about spam rates, reputation, and more through Postmaster Tools.
To stop spam, Gmail actively filters emails. Sometimes, we might mark an email as spam and move it to the spam folder. We also try to find ways to reduce the amount of spam sent to Gmail. If we think an email might be spam, we block it.
We only block some emails that look like spam, not all of them. An email might be blocked if it contains words that look like spam or if the sender has a history of sending spam. If you're an organization or company that sends emails to personal Gmail accounts (@gmail.com or @googlemail.com), review the Email sender guidelines.
If you forward an email to Gmail and your domain also sends spam, learn about best practices for forwarding email to Gmail.