You can shut down an entire school district if you send the right email — or the wrong one, it depends on how you look at it.

Recently, an unidentified individual or group issued a number of jihadist-style terrorist threats to schools around the country. Officials largely dismissed them as shallow pranks, but one such email was sent using an anonymous email service called Cockmail, which, despite the hokey name, was frightening because:

1) It contained a threat against the Los Angeles school system and…

2) It couldn’t be traced.

The threat ended up displacing around 640,000 students for a day, which is a pretty serious reaction to receiving an email from a single-entendre domain. Disposable email addresses provoke that kind of concern.

Cleverly billing itself as “mail with cocks,” Cockmail is, of course, located at cock.li. Despite the ostentatious marketing, the site is almost entirely safe for work. Its value isn’t pornographic in nature, but technological—it offers a private email service that caters to those with a distinctly 4Chan sensibility, or a specific need for anonymity. That said, the service isn’t immune to the law. Vincent Canfield, creator of the email service, has tweeted about his participation with the subpoena he received in light of Cockmail’s involvement in the LA school threat.

While anonymous terrorist threats are far from a desirable use for such email services, there are a few worthy situations in which it is perfectly acceptable, even desirable, to use an email address that cannot be traced back to you. Here are three use cases.

Getting past “email required” blockades…

Marketers want your contact info, and you want access to content. For a long time, you might have had to grin and bear it as you typed in your valid personal email address, but this stops today.

For those situations where you need an email address that you just don’t care about and you need it immediately, you need a service like Mailinator. It is a publicly accessible email domain: You can gain access to any address “@mailinator.com” by simply typing it in on the homepage.

For those occasions when you absolutely must enter a valid email address when you absolutely don’t want to, Mailinator is a godsend. It is perfect for super-short-term anonymity in situations where you don’t care about a reply, or only need to click on a verification link sent via email.

Signing up for a private service…

Your life is your own. Maybe you need to keep certain parts of it completely siloed. Whatever your tastes or motivations for such compartmentalization, you’ll likely need a dedicated email address that you can use exclusively for off-record activity. It could be a hidden Gmail account, or it could be something like Cockmail, but it needs to be more private than Mailinator. This use case calls for something longer-term than the one-time bypass of a blocked webpage. A service like SpamGourmet fits the bill nicely, offering you password-protected email addresses that are easily customizable to only retain a certain number of emails.

If you absolutely didn’t want to go through the trouble of creating a new email address from scratch, you might consider coming up with a remarkably unique Mailinator address that no one else could guess, though this is certainly not as secure as a standard password-protected email.

To prevent harassment…

If you’re trying to protect yourself from unwelcome communication on the Internet, it helps to have an email address that you only share with close friends and family. Make sure that your contacts know that yours is an email address that isn’t shared casually, that it should be respected. It could perhaps present itself as a pleasant respite from your conventional inbox, jammed with work emails and ads. Have a more-private account that’s reserved for genuine communication with people you love and want to hear from. This wouldn’t be an address you use to complete your Amazon orders, it’s more important than that.

To bring it all home, it gets increasingly difficult to keep your privacy intact online over time. But technology is capable of answering the call to keep your inbox free of unwelcome spam, ugly harassment, or emails you definitely do want to receive—just not right next to everything else.

May your discretion guide you.