Guerrilla Mail

What it is

Guerrilla Mail provides time-boxed disposable inboxes (1 hour by default) at multiple shared domains. Users can pick a custom local-part. The inbox content auto-deletes when the timer expires.

Why signup forms see so many of these

Time-boxed nature means addresses are effectively single-use. The service publishes its blocklist of domains openly, but new throwaway domains under their ownership appear regularly. Aliases like sharklasers.com and grr.la are often missed by hand-maintained blocklists.

Known alias domains

Naive blocklists that only block guerrillamail.com miss every alias below. These are all routed through the same provider.

• guerrillamail.com
• guerrillamail.net
• guerrillamail.org
• guerrillamail.biz
• guerrillamail.de
• sharklasers.com
• grr.la

The actual production list of Guerrilla Mail-operated domains is larger. CheckDisposable Email tracks all of them, updated daily.

Block Guerrilla Mail the right way

Send the signup email to GET https://api.checkdisposable.email/v1/check?email=<email> with a Bearer API key. If is_disposable is true, reject the signup.

// node — block Guerrilla Mail + all aliases in one call
const r = await fetch(
  `https://api.checkdisposable.email/v1/check?email=${encodeURIComponent(email)}`,
  { headers: { Authorization: `Bearer ${process.env.CDE_KEY}` } }
);
const { is_disposable } = await r.json();
if (is_disposable) {
  return res.status(400).json({ error: 'Please use a real email address.' });
}
// continue with signup

Free plan: 500 checks/month, no credit card. No card. Get a key →