(GH-6) make the email secure in appveyor

appveyor.yml

@@ -22,7 +22,8 @@ environment:
   github_user_repo: 'YOUR_GITHUB_USERNAME_HERE/chocolatey-packages' #https://github.com/chocolatey/chocolatey-packages-template is 'chocolatey/chocolatey-packages-template'
 
   # Email credentials - for error notifications
-  mail_user: YOUR_EMAIL_ACCOUNT
+  mail_user:
+    secure: YOUR_EMAIL_ACCOUNT_HERE_ENCRYPTED_STRING #https://ci.appveyor.com/tools/encrypt
   mail_pass:
     secure: YOUR_EMAIL_PASSWORD_HERE_ENCRYPTED_STRING #https://ci.appveyor.com/tools/encrypt
   mail_server: smtp.gmail.com