- Go to https://gmail.com
- Click on Details (it's near the bottom right corner of the Gmail mailbox screen)
They used to show the IP address (see “Suspicious sign-in prevented”. Suspicious or not?). Only Google could say why they stop sharing it in the alert.
Related
- Strange address appearing in my Gmail's last account activity
- How accurate is the Gmail account activity listing?
- How to see time that one IP login on Gmail?