When you say "the e-mail" do you mean your personal e-mail reader, or a preview of the mail that will be sent? The change from
cañon guía åäö
caÃ±on guÃa Ã¥Ã¤Ã¶
is a single error that happens just once. So either the e-mail isn't sending the right encoding information, or your e-mail reader isn't seeing it.
If you're talking about e-mail that has actually been sent, look at the "content-type" in the e-mail header; it should give an encoding. (Frankly I have no idea where it gets the information. Mine apparently defaults to Latin-1, but silently jumps to UTF-8 when needed.) Then at least you'll know which end is making the mistake.