Hi Anton
It is true I am new to trying to sort this out. But I have been reading and researching about it and the fact that you even have to get into complex workarounds is a little much I find. This thread and another independent web page here and there is all there is about this issue, which I find strange. I am trying to migrate from Google, and I have to say, in the Gmail setup, everything is VERY open and flexible and setup-able. You just tell it the email address you want to send from and away you go.
I have tried to set this up on my computer, although I am nervous about deleting my account (does that then delete my iCloud stuff, or is it just the Mail settings? All bit blurred the way Apple presents it with Yosemite and iOS8 - or maybe it is just that I am new to it). Anyway, I have tried simply replacing my iCloud email address with the one I want in Mail preferences, but it seems that, even if I select the Gmail server, Mail tells me that my email address is not verified. Which is strange, as it is my main address for all my iCloud, etc. logins, and is stated as verified and primary and so on on that part of the system. Even if I got that working, I don't like the idea that if I send mail from my iPad, I will have to remember to manually select my 'other' non-iCloud address, every time I want to send a mail. Not necessary, I say!
Or have things changed? I am indeed hoping that my frustration is unfounded and that you will put me in my place and tell me you are doing exactly everything I want to do with no problems! Please let me know!
Jon