koko ha kenmo no shokuminchi. [転載禁止]©2ch.net
Yahoo! Japan email barely works.
When I got an e-mail from U-Haul, my gmail account received it but Yahoo! Japan account didn't. Moreover, when I couldn't send an e-mail to a comcast e-mail account from my Yahoo!JAPAN account, but I could from gmail.
I recommend you to use gmail rather than Yahoo!Japan e-mail.