However it provides a method of tracking someone's movements over the past year. Those people involved in high level crimes or wanted by authorities are less likely to stay in one location. If you have IP records which usually map to a specific location for that time, then you can track their movements and do real investigation to find associates and other information.
Any real technological criminal is going to use 1024-bit or 2048-bit key-based encryption on their sensitive mails so keeping the contents wouldn't provide much information. If you're worried about being spied on then use encryption yourself. PGP can be used with just about any email system.
Personally, I am not worried about it. I don't plan crimes via email or knowingly associate with criminals.The most dangerous thing that someone can find out about me through emails is my daily bank account balance. Even if that email contained an account number and password, they can't login without having my cellphone in their possession and knowing my secret questions.
I can't see how people are concerned about this with the way email works anyway. Your emails bounce from server to server in an unencrypted format. Any server along the way could belong to a law enforcement agency that captures all information. If you use SSL to login to retrieve email, that only protects the connection between your computer and your email server. It doesn't protect from the sending server or any stops in between. If you're concerned about privacy then you already use PGP for your emails and only give the public key to people you trust. If you don't then your just blustering about your concerns.
so because of the few they track the lot ?
Thats like saying if the police are raiding a house on a street then they may as well raid them all.
If you going to plan crimes you not going to send it in an email anyway are u - surely no one is that dumb.