This is "Working as Intended" (and Google told him exactly that). Gmail and other providers have to split the balance between privacy and security. If you use

This is "Working as Intended" (and Google told him exactly that). Gmail and other providers have to split the balance between privacy and security. If you use the web interface and they authenticate your device directly, Google hides your IP and takes responsibility as the "source" of the email. If you're using SMTP it is possible you could be relaying mail for others (even possibly as an open relay) and they will disclose the IP of your client or mail server.