Comment by treetalker

In reading the other responses, I feel it might be good for you to remember that your current inbox is a result of your system. To solve your problem long-term, you'd do well to ascertain what your system is and how it works; and then figure out where and how to intervene in that system. Perhaps some of the suggestions in other comments will help patch things up; or perhaps you'll want to start over with a simple system that works.

I know the foregoing might sound trite, but it's coming from a place of experience.

My system involves processing my inbox to zero on a regular basis and processing certain types of emails in a batch as infrequently as necessary.

In the inbox, I start by immediately unsubscribing from any list I get put on from senders I recognize (if I want the information, I figure out a way to get it by RSS). If I don't recognize the sender, or if unsubscribing didn't work, I mark it as spam.

If the information is something I need or want to receive by email, I need to do something with it, and it comes at predictable intervals, then I use filters to apply an appropriate label (grouping similar items) and skip the inbox; and then I have a system to process those emails all at once at an appropriate interval. The batching saves time; keeps my inbox clean (which also saves time and mental energy); and it solves the problem of senders who send the same information or same email multiple times.

I take the time to ask myself:

What is this?

Do I receive it regularly?

Do I want to receive it?

How do I want to receive it?

Do I need to do something with it?

How frequently do I need to do something with it?

Can I do that thing all at once with multiple items from this and similar senders?

It takes time to answer these questions and to set up rules and systems to handle the items, but that investment pays dividends and quickly starts to reduce the amount of time spent in your inbox.

And if you haven't already, consider learning the basics of Getting Things Done or a similar productivity system.

P.S.: Also ask yourself why you're "signing up for everything" in the first place. That seems to be one of the root causes of your situation and an important part of your current system to think about.