How do you make sure you don't miss important emails?

I’ve realized that the problem with email isn't always the number of emails — it's knowing which ones actually deserve your attention.

I've personally missed opportunities simply because an important email got buried in my inbox.

So I'm curious:

• How do you currently keep track of important emails?

• Do you use labels, reminders, filters, or another tool?

• Have you ever missed an opportunity because you didn't notice an email in time?

I'd love to hear how everyone handles this. What actually works for you?