That would be extremely difficult to do. Even if somebody were able to get the ip address that an email originated from, in order to find out the physical address of the person using that ip address they would have to contact the Internet service provider that assigned the ip address, find out which customer the ip address was assigned to, and then track down the physical address of that customer. Most Internet service providers take their customers' privacy very seriously and would be reluctant to release any information of that kind. In fact, there may be laws against it and they may only release it by court order. (I say may because I don't know, but that would be my guess.)
While you can do a geographical lookup of an ip address, it only tells you the approximate location of the Internet service provider it was assigned to, not the customer whom the Internet service provider assigned to it, though with local Internet service providers these are often one and the same. Even then, though, you're only getting an approximation of city, state, and zip code.
You can prevent even this by doing your web surfing through a proxy server that replaces your ip address with it's own... if you're concerned about this sort of thing.
When I first got a computer I wanted to look up old high school friends. Its was a real pain, I had to find their email via places like classmates.com and a few I had to actually pick up the phone and call them
Don't want to scare anything though, but I know with IP addresses you can get a certain area of where someone is. Ever been on a website and they give you a website close to where you live? I saw one ad at Tom was on the 'net and it was " Meet Singles In (town)"
I of course questioned that and he told me how it was able to be done.
But with proxy servers you can be living in Rhode Island (USA) and through a proxy server get an IP address of someplace in China... really cool if you think about it.