Most small to medium ISPs in the US have decided that their users will not communicate with people in Asia, and subsequently blocked IP ranges assigned to Asian countries. If they are nice they will bounce your mail and tell you "your country is blocked", if not they'll just blackhole it. The idiots will even drop mail sent to their postmaster address.
They won't address the issue until your recipient threatens to switch ISP.
If you can send mail to these domains through your ISP's SMTP servers, either your ISP have already done the kicking and screaming for you, or they have their own mail relays in the US that don't get blocked.
Most large ISPs will bounce mail if they can't reverse lookup the IP address of your SMTP server.
I know for a fact that Toyota's mail server specifically blocks all mail from Yahoo and Hotmail.
And yet still more reliable than many ISP or internal hosts, the biggest advantage is that most companies will specifically configure their filtering to allow mail from the big free email providers.
A lot of companies actually block the free e-mail providers for fear of mail abuse by their internal users.