How to Know If Your Email Has Been Compromised (and What to Do)

Breaches are more common than you think

Hundreds of millions of credentials are leaked every year. LinkedIn in 2012 (117 million accounts), Adobe in 2013 (153 million), Dropbox in 2016 (68 million), Twitch in 2021. These are just the breaches that became public — many others never come to light or take years to appear in accessible databases.

Chances are your email address appears in at least one of them. Not because you did something wrong, but because some service you used didn't protect its data properly.

Why email is the key to your digital identity

Your email address isn't just a contact method. It's the primary identifier for most of your online accounts and, most importantly, it's the password recovery gateway for almost everything: your bank, your online store, your password manager, your social networks.

If someone has access to your email — or even just your address and password from another service you reuse — they can chain access to multiple accounts. This attack is called credential stuffing: attackers take lists of leaked credentials and automatically test them on thousands of different services. It's cheap, massive, and very effective precisely because people reuse passwords.

What data is exposed in a breach

Not all breaches are the same. Depending on the compromised service, the exposed data may include:

• Email only — the mildest case. Increases the risk of targeted phishing.
• Email + password in plain text — the worst scenario. Direct access to all accounts where you use that password.
• Email + password hash — requires the attacker to crack the hash, which is easy if the password is weak or if the hash is poorly implemented (MD5, SHA1 without salt).
• Email + personal data (name, phone, address, date of birth) — enables very convincing social engineering attacks.
• Email + payment data — the most financially damaging scenario.

When SecuryBlack detects your email in a breach, it tells you exactly what type of data was exposed so you can prioritize your response.

How the scanner works

SecuryBlack checks your email address against known breach databases using k-anonymity: your email is never transmitted in plain text. Instead, we only send a fraction of your address hash, which allows checking if it appears in the database without our servers ever learning your full email.

The process is:

1. You enter your email in the scanner
2. We verify it against our database updated with the most recent breaches
3. If it appears, we show you which breach, on what date, and what data was exposed
4. If it doesn't appear, perfect — but with a free account we can keep monitoring continuously

The difference between a one-time check and continuous monitoring is important: breach databases are constantly updated. An email that doesn't appear today may appear next week when a new breach is published.

What to do if your email was compromised

The response depends on the type of data exposed, but there's a base protocol that works in all cases:

1. Change the password of the affected service immediately. Not tomorrow, now. If you no longer use that service, consider deleting the account.
2. Check if you reused that password on other sites. If so, change it everywhere. This is the most tedious part but the most important.
3. Enable 2FA on critical accounts if you don't already have it. Email, bank, online store, password manager. The second factor makes a leaked password much less useful to an attacker.
4. Consider using a password manager to generate unique passwords per service. Bitwarden (open source, free), 1Password, and KeePassXC are solid options.
5. Monitor your email continuously with SecuryBlack to receive automatic alerts when your address appears in future breaches.

If the exposed data includes personal information like address or phone, pay special attention to phishing emails in the coming months: attackers use that data to build convincing messages that look legitimate.