[Phalanx]

True they can find out if you open it by various methods, some of which can be defeated.

The most common method is read notifications provided by MS-Outlook, which is why I will never use Outlook or Outlook Express for mail. So make sure your email program as the ability to deny receipts for mail both received and read.

They can also tell by using java script within the e-mail, hence I disable java-script support in emails.

They also love to use click this link "to check on", or "to unsubscribe", so don't do that either. Don't click on links even to unsubscribe.

I've been very successful in getting very very few spam/phising emails for many many years following these concepts.

One final point is to never publicly post your email address in any web page anywhere. That prevents spammers from collecting email addresses from popular web sites.