I have e-mailed friends and family the same way I would in a private phone conversation. Some people have e-mailed me personal things that are for no one to read but me.
Thinking that all of these e-mails or other online activity is stored somewhere is I think a total violation of anyones privacy. I can see if it needed to be kept for a few days but years??
Jim
Very few if any ISPs store E-mail. I've never heard of one that does. Those are only stored on a server for a short time while they're "in transit" unless the user has set up their end of it to keep copies, and it is generally not the default. Imagine the huge amounts of data that would need to be kept to keep copies of all E-mail sent back and forth. I'm not sure it would even be possible.
What "they" are probably asking for is to store the originating IP addresses only. Most ISPs only keep that for a period of time ranging from zero to a few months, or in rare cases, as long as the account is active.
That said, you should realize that E-mail goes through a number of computers on the way to it's destination, and any system administrator anywhere along the way CAN read any data going through their systems if they are so inclined. And they don't even need a warrant!
But like I said, they're probably too busy, and really don't care if your Aunt Matilda had an affair with the pool boy.
If you want to be assured of privacy (at least until quantum computers are developed) use PGP or a similar product or stick to having your conversations in the Cone Of Silence.