Από το Learn more του Google:
"...If you always or most often sign in to Gmail using a single computer, your IP address should be the same, or start with the same two sets of numbers (for example, 172.16.xx.xx). If you're seeing an IP address that differs greatly from your usual IP address, it could either mean that
- you've recently accessed your mail from a different location, or
- that someone has accessed your mail. Your current IP address is displayed below the Recent activity table.
Please note: If you have POP3 or IMAP enabled, you'll see this in your recent activity table. If you're fetching your messages to another Gmail account, a Google IP will appear; this is simply because the messages are being fetched through our servers.
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If you think your account has been compromised
You'll need to change your password and your security question. The first step is to read our suggestions on choosing a good password to make sure that your new password is secure. Then, follow the instructions in How do I change my password? to update your password."