|Your Internet Service Provider assigns your modem an IP address. It's often dynamic, but some ISPs give static (non-changing) addresses. The IP address they assign you is often called the "outside" or "Internet" address, because that's the one Internet servers see. If you have multiple computers on your network, they're likely connected together through a router, which is then connected to the modem. The router, if DHCP enabled (as often the case), will assign each computer on the network an IP address. Internet servers don't see your computer's specific address if it's assigned by your network router.|
When you send an email, the attached IP address is that of the email server. Your email provider surely has your outside address logged for that email in the event they need to track you down for crime.
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