If you are a BT Total or BT Infinity customer and only use the free Yahoo! email account rarely then it is time to sit up and take notice, particularly if the Yahoo! address is the one BT use for communications.
While most people check email everyday, with the number of accounts people acquire over the years it is possible that some people only check certain accounts once or twice a year, and it seems BT Yahoo! Mail is implementing a new a clean up so that accounts that have not been accessed for 150 days will be vapourised.
To keep an account active you need to access it at least once every 150 days via one of the following methods:
The clock started ticking on 18th January 2013, so the first inactive accounts will be deleted on/after 17th June. For those worried about others subsequently re-using an email identity once the account has been deleted that email address will not be given out to anyone else.
So if you have signed up to various other online services using your BT Yahoo! email address years ago, but have stopped using the address apart from when resetting passwords to access sites, and you don't intend to make more use of the BT Yahoo! mail, then we would suggest changing registration details before its too late.
As for why BT Yahoo! mail is implementing this policy, we can only assume its part of a cost reduction exercise. It seems unlikely (but it is possible) that this is linked to the ongoing complaints from people that their Yahoo! account has been hacked, and in some cases people are adamant they have not received or clicked on any links from rogue e-mail or websites.