How To: Perform User Security Checklist
Step 1: Check Last Account Activity to see your Sign-in history.
Step 2: Change your Password https://myaccount.google.com/signinoptions/password
Step 3: Check Gmail Settings in case any unknown configuration is found.
1) Review Reply To Address
2) Check for Unknown Filters.
3) Check whether there is Unknown email forwarding, and enablement of POP & IMAP.
4) Check whether the Vacation Responder is Turned ON.
5) Check whether your Account is Delegated where User can send emails on your behalf and access Mailbox.
Step 4: Review and Remove Recovery Phone & Email Address https://myaccount.google.com/security?gar=1
Step 5: Review and Remove Connected Apps https://myaccount.google.com/permissions?gar=1
Step 6: Review and Remove App password. App Passwords are the way to access your account on Mail Clients during 2 Step verification is enabled.
Step 7: Lastly, Review Self Security checkup https://myaccount.google.com/security-checkup?gar=1
