Let me start off with a quick story - Once an employee of mine clicked a link in an email that directed them to a site that LOOKED like eBay.  That employee then entered our username and password on that site - within hours our eBay store had been closed and over 20,000 auctions have been ended!  It tooks weeks to recover and cost us thousands of dollars!  Now I will explain what we do to avoid this from ever happening again - it is simple and can save you from having to go through what we have gone through.

Here is the #1 way to identify if an email you are receiving is really from eBay (or paypal, or any other legitimate site) - or if it is a fake email sent by someone attempting to steal your passwords and other personal information (this are called phishing emails).  Being a large business, we receive a few hundred emails a day, often many that are fake emails that impersonate eBay.

#1 WAY TO IDENTIFY:
These fake emails will ALWAYS have a hyperlink in them (this is usually a word or set of words that will direct your web browser to a different site - usually these hyperlinks are BLUE and UNDERLINED - PICTURES can also act as hyperlinks).  They need to have this hyperlink because it is what will bring you to their fake website that will look just like a legitimate website, such as eBay.

The first step is to make sure your internet explorer STATUS BAR is turned on.  You should already be in internet explorer if you are reading this, so all you have to do is go to the top of your internet explorer window and there are a few menu bars - one of which says VIEW.  Click on that and a drop-down menu will appear - after that appears, simple make sure STATUS BAR is checked - if it is not, click on it and it will become checked.  What this will do is turn on a bar at the very bottom of the internet explorer screen - for example, my status bar has a picture of the internet explorer icon on the bottom left corner of my status bar and a globe with the word "Internet" on the bottom right side of the status bar.
Now, back to the emails - when you HOVER your mouse over one of the hyperlinks (Just put the cursor over it, do not click on it!) in a questionable email, a web address will appear in that status bar - this will tell you where that hyperlink will take you to.

For example below is a hyperlink to "www.ebay.com"

EBAY HOME PAGE

When you hover over that link you will see that in your internet explorer status bar, it says "http://www.ebay.com" - this is telling you that if you click on that link, it will bring you to ebay's homepage as you would expect.
Now hover over this hyperlink below:

EBAY HOME PAGE

That LOOKS like it should be a link to eBay's homepage by the way it is titled, however when you hover over it, your status bar says "http://stores.ebay.com/DISCOUNT-GAMES" - that is a link to my eBay store homepage (I have to use ebay-directed links in these guides, otherwise I would have used a different web address). 
The point is, I can change the hyperlink to be ANYTHING I want - I can title it anything I want, but then have it go to ANY site I wanted.  This is what the phishing emails do - they will have a link which you think is going to bring you to ebay, but the link will be different - the site may actually LOOK like an ebay sign-in page, but when you look at your status bar, it will say a crazy website that often has nothing to do with eBay!
The bottom line is this - CHECK THE STATUS BAR EVERY TIME BEFORE YOU CLICK ON A LINK IN A QUESTIONABLE EMAIL!