How Much E-mail is Useful These Days?

I started using email in 1992 when I started at NJIT.  Back then it was a novelty as it made it easier to communicate with friends and colleagues.  Over the years e-mail has become more of a waste of time than anything else.  I have:

• One account for work
• Two AOL accounts
• One Gmail account
• One Yahoo Account

How many of these e-mails are useful these days?  On all accounts most e-mail is advertising.  After making online purchases I am bombardeded by emails advertsing more products from that vendor.  Very few emails are useful these days.