Check the email address(es) you added as test recipients in your contact data. Is it (are they) correct and complete?
Are you checking the right email account(s)? For example, if you sent the test to your AOL account, it won't show up in your G-mail account unless you have email forwarding activated in your AOL account.
Did your corporate email server bounce the eMessage? Check your Track Results page for the test eMessage (after waiting a few minutes for it to travel through the email delivery system) and look at the Bounce statistics.
Check your contact record details for the email address in question, or your Email OptOuts list to be sure you haven't accidentally unsubscribed from your own emails. (It happens!)
Replicate the eMessage and send it to a different test email client (if you sent it to your AOL account but did not receive it there, test your Yahoo account, etc.). If you receive the test in certain email clients but not others, you can conclude that either the receiving server or your personal email settings caused the eMessage to fail in a particular email client.
Some webmail programs (like AOL, Yahoo, Hotmail, etc.) delay delivery of what they consider "bulk mail" to recipient accounts by up to 24 hours. You may just need to wait it out.
If sending tests to corporate email accounts (yours or an outside recipient's), SPAM firewalls may be bouncing your eMessages. You may need to contact your or your recipient's IT department to have them whitelist NewPanda's IP servers (see Item #9 below).