I'm going to put my neck on the chopping block and say I agree with George on a lot of points. I'm still using the Yahoo mail address I set up 4 years ago (and which I've used to sign up to an awful lot of sponsors - I shudder to think of the hassle of changing it over).
Of course, I also have my domain-based email address which I use to submit... and numerous other addresses to use for looking businesslike. So I think it's handy to have both.
One of the main reasons I still like Yahoo mail is the spam filtering, and also the fact that I can read it in Mozilla. The domain-based email that I use for submits began to fill with spam the day after I first used it, and the filters on that mail program are quite useless.
With Yahoo you can now set it to collect mail from normal pop3 addresses and to use a
domain@domainname.com address as the reply address. So the two things can be combined.
Of course, you still have to put up with yahoo ads, so it's not perfect. And I can see the point being made about the impression it can give. Nonetheless, not all people who use free email addresses are scammers
Hopefully this post won't make you think I'm unbusinesslike.
It's just a preference.