If you wish to check the email headers for any email from gmail, you can do it by logging into your gmail account. At times your server administrator require them to troubleshoot the issues you face.
Login to your gmail account and click on the email for which you wish to check the headers. On the right hand side click on Show Original as listed in the screen grab below.
(https://www.milesweb.com/hosting-faqs/wp-content/uploads/2014/02/gmail-headers.jpg)
It will open the email headers in new tab. These email headers hold all the information of the email; Server IP, Server Hostname, IP from which email was sent, Location, DKIM-Signature, Date, Content-Type, etc. Select all, copy & provide it to your server administrator.
Hope this helps :-)