This is what I was told this morning via Whatapp. This was for a flight departing the UK on June 3rd 2020.

That has now been changed to an open ticket for you, and your booking reference will remain the same. You can re-book your flights for any dates before the 31st May 2022, and you’ll just need to get in touch to re-book your ticket before the 31st December 2020. No change fee will be charged, but if travel is taken on or after the 1st December any increase in fare will apply.
Once you're ready to re-book your flights, just get back in touch and we can process this with you.

No email will be sent as the ticket is not reissued, you can see everything online.