Bill has asked a legitimate question: "So what if your ISP is not particularly ethical?"
Two things you need to consider before using email to transfer potentially actionable or sensitive information around the place:
1. Most ISPs are working at very low margins and will be looking for any way they can to make a buck.
2. Not all ISPs are ethical in the way they treat their customers, never mind in respect of the data on their servers.
You and I may not have much to lose this way; but companies who use an ISP whose business ethics are dodgy are just asking for trouble.
I have problems with using any any supplier of services who acts unethically whether that affects me directly or not.
