If you use gmail, there are a couple secrets hidden in the gmail "help" and you can create a "new" email address for (almost) every website you visit, and they all come to one gmail account!
NOTE: I'm going to truncate "@gmail.com" to just "@gmail" in my examples.
GIVEN: a normal gmail email address is in the form"user.ID@gmail" and is notcase-sensitive.
Periods (.) on the left of the @-sign are ignored."user.ID@gmail" is the same as "u.s.e.r.i.d@gmail" and "userid@gmail"
When I give emails to companies, I leave out the periods as a personal hint. Family, friends and (most) user forums etc get addresses with periods.
You can add a plus sign (+) between your user ID and the @-sign. For example, "userid+53bank@gmail" or "userid+sears@gmail" both work, and come to my account "user.ID@gmail' account.
Now, if I [you] get an email addressed to "userid+sears@gmail" and the email is an ad for 5/3 Bank, or PayPal, or Amazon etc you know it's bogus - Why would 5/3 Bank use my Sears email?
NOTE: a few sites won't accept an email address with a plus sign (+) in it, but they're rare. As I said above, I leave the periods out of addresses I give to companies. So if the user ID has periods and it's from a company, I view it with suspicion. If I need to, I can use my browser's "saved logins" to look-up my login for the company - if it doesn't match, then I'm even more suspicious!
TO CHECK THE EMAIL ADDRESS used for an email, open the email, click the down-triangle next to your user ID, and view the email headers. Here's a screenshot (with my real information altered)
Gmail's SPAM filter is pretty darn good. A few valid emails occasionally get sent to the SPAM folder, so I review and empty the folder every day to make sure 1) don't miss a valid email and 2) SPAM reviews are easier/quicker.