Tomorrow, Yahoo will release email addresses that have been inactive for the past 12 months. Those looking to graduate from number-filled addresses can upgrade to something more memorable, like john[at]yahoo.com.
Users have put in requests to claim dormant IDs since July 15 and will find out Thursday if they got the username they wanted. The program to free up and recycle old Yahoo IDs has raised security concerns. Wired's Mat Honan, whose hacked accounts made headlines last summer, called it a “spectacularly bad idea” because of the potential for people to use password resets to steal the original users’ identities.
Yahoo responded to these criticisms by saying most inactive IDs aren’t associated with a mailbox. Furthermore, it implemented a 30-day deactivation period, unsubscribing dormant accounts from newsletters and other marketing emails. Businesses, financial institutions, and social networks have also been sent notifications about deactivated email addresses.
this is why you only need to keep email flowing through the account and forward it to another active account to prevent loosing it.