Now a days email spoofing has been a very common act, there are tons of softwares which can be used for email spoofing. Internet emails are designed to

carry the IP address of the computer from which the email was sent. This IP address is stored in an email header delivered to the recipient along with the message. Many people have never seen an email header, because modern email clients often hide the headers from view. You can enable the header if you want

1. Log into your Gmail account with your username and password
2. Open the Email in Gmail you want to trace
3. Next click on the arrow that’s to the right of the Reply link and choose Show Original from the list
4. You may copy the headers and use my IP address detection script to ease the process
5. If you want to manually find the IP address then proceed to next step
6. Look for Received from followed by the IP address between square brackets
7. If you find more than one Received: from patterns, choose the last one
8. Then track the IP address of the sender

Note that this will not work if the sender uses anonymous proxy servers. Also if you receive an email sent from a Gmail account through the web browser, you may not be able to find the real IP address because Google hides the real IP address of the sender