Emails gone (?)

Emails gone (?)

Dear Zoho-Team,

I've noticed yesterday that my emails go back to end of 2016 only (everything older has gone).

Can you tell me please:

a)  when did I become a ZOHO user?
b)  where have my older emails gone? 

This is really annoying, please tell me that they are not gone for good!!

Best regards
Antonio