When an email has an embedded image in Gmail, can the sender trace IP?

"This has changed between now and the answers from 2009. According to Google, images can no longer be used by the sender to obtain the IP address of the recipient:

Some senders try to use externally linked images in harmful ways, but Gmail takes action to ensure that images are loaded safely. Gmail serves all images through Google’s image proxy servers and transcodes them before delivery to protect you in the following ways:

Senders can’t use image loading to get information like your IP address or location.
Senders can’t set or read cookies in your browser.
Gmail checks your images for known viruses or malware.

In some cases, senders may be able to know whether an individual has opened a message with unique image links. As always, Gmail scans every message for suspicious content and if Gmail considers a sender or message potentially suspicious, images won’t be displayed and you’ll be asked whether you want to see the images.

Just to reiterate that last paragraph: Please note that it is possible (indeed common practice) for the sender to obtain the information on whether or not you opened the email and at what time you opened it. This is a common feature of standard mail services (e.g., Mail Chimp)."