Slight updates: I have two addresses, a Gmail one and one (as I said) that doesn't look like a Gmail address but now automatically gets translated to https://mail.google.com etc. Earlier I was trying to send from Mail to the plain Gmail address which didn't work. When I try sending from Mail to the other address (my main one), I see that in the outgoing message the code does get highlighted as a link.

On the iPod, at the moment I have no way to use Mail (though I can work on that); I get all my mail through Safari instead. There, the message's content does not appear as a link. So I think the problem must be on the receiving end, a problem with receiving the file within a browser? Does that sound right?