Cryptocurrency transactions are irreversible. If you send cryptocurrency to a third party, you cannot reverse it or stop payment. When you send cryptocurrency to a blockchain address, you must be certain of the legitimacy of any involved third-party services and merchants, and only send cryptocurrency to entities you trust.
Pro tip: If it sounds too good to be true, it probably is.
Extortion scams
Scammers will often use information sourced from data breaches at other websites to trick you into thinking that they have more information about you than they actually do. For example, they might show you an old password that you may have used to affirm that their scam is legitimate.
If you are victim of an extortion scam, please immediately take these actions:
Report the email as spam to your email provider.
Run a precautionary malware scan on your computer using a reputable tool like Malwarebytes.
If you recognize any passwords included in the extortion email as one you currently use, change it immediately across all websites.
Contact your local authorities and file a police report. Have the authorities contact Coinbase directly. Coinbase is committed to full cooperation in all law-enforcement investigations.
While these messages can be alarming, they are almost always fraudulent. For steps you can take to make your account more secure, please see this help page.