E-mail tracking blocker software

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Can anybody give me a good tip on a good e-mail tracking blocker software.

I don't like the idea of the sender to send in a mail that's being received by me a little program that tell's te sender i the receiver have received my mail and maybe even opened it.
I regard this as spyware despite the good intentions of perhaps the many users.

I hate to think that spammers might use this tracking software too.