Recently Gmail has introduced a new preview tool, which enables Gmail users to view an address on Google Maps right inside the Gmail web client. See the screenshot of Google Map embedded with the mail which was send my friend from 123greetings.com.
If you want to enable the Google Maps previews,
1. Go to the Labs tab in the Settings.
2. Search for “Google Maps previews in mail”
3. Select Enable
4. Hit save and you’re done.
Gmail will automatically detect any addresses in the body of the message and list them below along with the embedded Maps. Currently,this only works for US addresses, but Google says it will eventually enable it for all addresses.