A bunch of people use my email address for signing up to all sorts of websites (I have a common name, and my email is basically my name @ popular email provider). It is annoying to receive all this spam (usually I can unsubscribe), but the worst ones are people using my email for their bank accounts.

So now I get multiple password-protected monthly statements every month, and there is no way to unsubscribe since it's a bank statement. And the email subject doesn't have the full account number, and the email is from a no-reply address. Contacting the bank has been useless even when I found a way to do so. The most annoying one is from a bank where I have an account of my own (they used a capitalized version of my email address, which the bank thinks is a separate email), and so I can't block them all emails from this bank either.

The one fun time was when someone (in Asia) would frequently place food delivery orders using my email, and this service would send multiple emails for each order. Frustrated, I canceled their order once directly from the email, after which this particular problem stopped.