How does password reuse enable compromise?
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Think about every service you've signed up for over the past few years. Fitness apps, shopping sites, old forums, that one tool you tried for a week. Now imagine one of them gets hacked. If you used the same password there as you do for your email, attackers don't need to target you directly. They just try the leaked credentials everywhere until something opens.
That's the core mechanic of credential theft through password reuse. A data dump from any breached site becomes a skeleton key. Attackers run those username-and-password pairs against Gmail, Outlook, and other email providers automatically, at scale. It's called credential stuffing, and it works embarrassingly often.
Your email account is the one you really can't afford to lose. It's where every other "forgot my password" link goes. If someone gets into your email, they don't need your banking password, your ESP login, or your admin credentials. They just reset them. One key, every door.
For email senders specifically, this gets ugly fast. A compromised email account tied to your sending domain means an attacker can take over your ESP account, send spam through your infrastructure, burn your domain reputation, and lock you out before you even notice something's wrong.
The fix isn't complicated, it's just a little annoying to set up. Use a unique password for every account, especially your email. A password manager (1Password, Bitwarden, or similar) generates and stores those for you so you never have to remember them. Then turn on two-factor authentication for your email and your ESP. Even if a password leaks, 2FA means the attacker still can't get in without that second factor.
If you're worried a credential is already out there, Have I Been Pwned lets you check your email address against known data breaches for free. Start there, change anything that's been exposed, and make your email account the most protected one you have.
If your sending infrastructure is already showing signs of trouble, don't wait. Our SOS hotline is free and we'll help you figure out what's actually happening.
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