Quick, lock the doors and close the drapes. Grab the kids and barricade yourselves in the basement. Bring food and water, and don’t forget to…
Oh wait… hang on — did you mean it was just your email address?
Phew…. ok, relax! You do have an exposure, but if it’s only your email your problems are fairly minor.
I’ll explain the details in a moment, but first let’s think about your real address, the one on the front of your house. Anyone passing by can see that too, no secrets there.
Email addresses are hardly secret… you give it out when you sign up on a website, when you fill out all sorts of corporate and government forms and when you enroll in customer loyalty programs at your supermarket or pharmacy. Likewise with your phone number, which used to be published next to you name and address in physical white-page phone books, and which is now available online.
With little more than your name and address from the phone book, I can Google you and I have a high probability of discovering your email address as well. It’s a very public thing.
What’s my real exposure?
That actually depends more on you than anyone else — you should always be suspicious of emails arriving from unknown sources, or containing pleas for money or help. Most especially, do not open file attachments in emails from people you do not know and trust. It doesn’t matter if the sender got your email address from the dark web or any other source.
All that said…
If all that’s on the dark web is your email address, and perhaps your name, there’s no real problem. However, if what was published also includes your social security number or financial / banking information, you may well have a problem.
Keep a sharp eye on your bank account and credit card activity (which of course you do normally anyway, right?). And consider contacting your financial institutions and ask that additional security be placed on your accounts. This may be inconvenient at times (credit card charges declined until you talk to a representative on the phone, etc.), but well worh it IF you have evidence that information beyond just your email address was published anyplace, dark web or bright.
I’m interpreting the phrasing of your question to mean that it was your email address that was published, not the actual content of your emails. If I’ve got that wrong and it was the content of your messages, you have been hacked and you have a potentially much more serious problem. Immediately change your password, or perhaps consider getting a new account altogether, maybe with a different provider. Also keep a sharp eye on your device(s), someone may have access you don’t realize.