As stated, yes...but it should not be easy. My e-mail server isn't even in my own state, but to get the mail into my outlook, it needs to know where to send it to, and that is the IP address of your modem or router. If LEO has the right justification, and the provider is not one to bend over easily, it takes a warrant. The IP is requested to be located, and with some work, it will link to your provider, then they need a warrant to give the information to your billing account...and that is how they get your address. Dial up? Your IP probably changes with each call. But your not safe. If asked what account had this IP at this date and time, the provider does have that information to give if pressed. If your paying for internet service, your provider knows what IP your account has at all times...depending on how long they keep records.
Using free wifi somewhere like a motel, that is tricky as hell as they know someone was in the building but not exactly where. Most ask to enter the room number and password before you can access the net. The password must be valid, but any room number will pass the test and your on-line.
There is also the thing called A Media Access Control address (MAC address) that is a unique identifier assigned to network interfaces. They may not know where you are, but they can identify what computer sent what ever. It is like a vehicle VIN number. Like a stolen vehicle can be put on a look out for list, if LEO has the time and money, they can flag the device on a look for list. If they go that deep into looking for you, you are in a heap load of shit.
Of course, how do you think your email ends up on the computer at your house?
Ask Al Gore.......
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pales in comparison to flame.