Why sender address in the email appears as my "admin email" instead of the "Sender email" set under General Settings ?

Question: Why sender address in the email appears as my "admin email" instead of the "Sender email" set under General Settings ?

Answer: The reason why this happens is due to the option "Communicate using sender email" probably unchecked under general settings.
 
If this is unchecked it means all communication will appear to be from logged in user and if it is checked then only all communication will appear to be from sender.
 
Hence you would need to make sure this option is checked and you will be able to see the correct sender address in the email notification.