Hello Guh.
This can very well be a troll, don't be afraid of such " mail "
To increase the security on your account, you can bind your phone number to your account. So you can get it back asap once something unauthorized have happened with your account.
What you can do is, to change your E-mail and Password, I do recommend you to get a new E-mail from Gmail, and bind your phone number in Gmail too, so you have extra security on your E-mail.
This is all what we can "offer" you, nothing else.
I hope this cleared your questions etc, tell us if it made u more comfortable about your account.