As tweeted in Japanese, found one of my primary e-mail addresses ended with 104.net was removed by the end of Nov 2011 (3 months ago). The e-mail address had been provide by CLUB BBQ (iSHARE Inc., Tokyo), they decided to finish all their free e-mail forwarding services, announcing us in the mid of Oct 2011. After their considerations reflected by their customers/users, the services were set to move the premium service named as CLUB BBQ premium. But couldn't notice any of their announcement due to dozen unread emails in one of inboxes of my gmail.com. ;-)
First hint about losing the address was Twitter's notification on top of the web version but thought it may be a trouble or bug on Twitter because there have been a number of troubles in emailing between the operator and users. At that time I didn't do anything for it. Tonight a few hours ago I just found the some notification on pc version of Twitter.com and then found the address is not available any more.
I need to change my registered e-mail address with this old one to a valid one for hours...