Sometimes, we receive an email and we don’t know the person who sent that email. In that case, we need to find the location of the email sender so that we can guess who the person may be.
To find the location, we need to find IP address of the sender. The Gmail isn’t including the IP address of the sender in the message if he is using Gmail’s web interface to send the email.
If the person is using the desktop clients such as Mozilla Thunderbird or Outlook to sent email, then the IP address is often included in the message.
Find IP Address of Email Sender in Gmail