Notes loss caused by email-account deletion
If your notes are really stored in your email account, you should be able to reconnect to the same email account over IMAP to gain access to your notes again. Do not configure the email account as POP3 for example.

However, if you really have a new MacBook, it is probably running El Capitan. With El Capitan notes are no longer stored on IMAP email accounts - in fact it is not supported at all. Most likely your notes are really stored in iCloud, and you need to relogin to iCloud or reenable Notes in the iCloud preferences to access them.