If you ever receive an email newsletter that you did not sign up for, don't unsubscribe from it via a link or an email response. Just report it as spam instead.
You Might Expose Yourself to Malware
If you click on an unsubscribe link, the site in question may attempt to install malware on your computer. If you keep your web browser, and your computer in general, updated, then the chances of this happening are fairly low. However, the risk is just not worth it when you can just report it as spam instead.
You Confirm the Email Account is Active
You are likely to receive more spam by confirming this account is active. Also, this makes your email address more valuable on the black market.
You Give Away Information About Your Computer
If you click the link, the spammers can set up the website to collect your IP address (which can approximate your physical location) and information about your computer, such as the browser you use, the fonts you have installed on your system, and your operating system. While something like the fonts installed can seem innocuous, all of this information contributes to your browser fingerprint, which can be used to track you online, even if you are using incognito mode.
Please don't report legitimate newsletters you signed up for as spam. It adds a data point to the spam filter engine of your email provider, and will make it more likely that other users of that email provider that actually signed up for the newsletter might have their newsletters sent to spam ↩︎