If a message looks like spam, a scam, or abusive content, Facebook Messenger usually provides reporting tools right inside the conversation. Open the chat, tap or click the message or conversation options, and look for a Report, Report Message, or Something Went Wrong option. From there, you can choose the reason, such as spam, fraud, harassment, or abuse, and submit the report. In many cases, you can also block the sender at the same time, which helps stop future messages from that account.
It is also a good idea not to reply to suspicious messages, not to click links, and not to share codes, passwords, or payment details. If the message claims to be from a business, person, or support team, verify it independently before taking any action.
If you are using Messenger on a web page or in a browser, the interface may show additional help or safety options, so it can be useful to look on the current page for any visible contact or support information. If the message is threatening or involves immediate danger, local law enforcement or emergency services may be the right next step.