I received a "Suspicious sign in prevented" email this morning for one of my Gmail accounts. I changed my password just in case but upon inspecting the email details it looks odd.
It was accessed by 209.85.223.131
which seems to be owned by Google (mail-ie0-f131.google.com). When opening up account activity I get 'Unknown' under access type. So it hasn't even logged whether it was accessed by a browser or by POP.
This all seems very strange. Should I be worried?
Best Answer
Any suspicious alert should be reviewed carefully. Other users could try to access to your account from other Gmail accounts. If you didn't enabled two step verification (2SV) yet, do it now.
From About 2-Step Verification - Google Accounts Help
The above article includes a step by step guide to enable 2SV.
References
Last account activity - Gmail Help
Detecting suspicious account activity - Official Gmail Blog