Greg, when did you receive this email? I am surprised to hear about this, because the Classic option was retired at the end of last year, and it was then offered with a limited time window for users to opt in and stay on that option, but that window has since closed. Or did you opt in, and now you lost that option? One of the conditions to keep it at Classic is that you don't switch your plan or let it expire.
With very little information from you, I could not provide much specific information. Sorry... If you can provide a bit more information, I am happy to explain better.