Anyone with an email address from Freeserve, Orange, or Wanadoo will find that it doesn’t work after 31st May 2017, and they won’t be able to access their account or send or receive emails.
Freeserve was bought by Orange years ago, and then Orange was bought by EE and now EE is part of BT. So the current owners have decided to shut down all the old email systems they have inherited.
Their explanation (and a full list of the affected email systems) is here.
If you want to know what your options now are, get in touch with me (preferably by e-mail to email@example.com) and I’ll try to help.