I have always been surprised that people accept that services like hotmail and many others take the liberty to add advertisements on outgoing mails, without the senders knowledge. When you send a mail from a hotmail (or gmx etc) account, you actually don't know the exact content of the mail you are sending. The recipient will be spammed with an ad, which you have never seen and of course, not explicitly allowed.
I find this incredibly rude and totally inacceptable.
Google, on the other hand, sends your mails out as you have written them, and doesn't add anything to them. As a Gmail user, you get ads in the mail interface, but you don't spam your correspondents. I consider this perfectly acceptable. If I don't like it, I don't use gmail. And Google's robots read my mail to traget the ads. They were also the first to aknowledge this, and state it clearly when I signed up for a gmail account. If you open a hotmail account, do you clearly see that they will add spam to all your outgoing email? Has anyone considered suing them?
(And of course, ther is the milder version of the iPhone, preconfigured to add the ridiculous "Sent from my iPhone" to outgoing mails. Which new users don't know about. And don't know how to turn off. (it's a pre-configured signature)).