Hello, been getting e-mails from someone - I think it may be a prank and someone trying to cause trouble. I have heard that the police can track e-mails back to whoever sent them - but how do they do this? and also, do they pin'point the exact pc it was sent off? would like some advice so I know who has been sending them and wether it would be worth asking the police about this.
No they can't - well they can't if the sender know's what he's doing.
As Ethel says there are headers to E-mails that show what servers they've been through but there are many servers out there that are set up poorly and are known as "open relays" it's very trivial to use these to be anonymous or even pretend to be someone else doing this to try to damage someone's reputation is called a "Joe Job".
There are many other ways to accomplish this but basically if you send a mail in good faith it can be tracked but if youo want to hide it's pretty easy and there's not a whole lot the police or anybody else can do about it