Zoho Mail BackUp

Is daily backup available as a part of a plan or for additional fee?
Do attachments included in back up as well?

Right now I am using IMAP account. So I always have my emails backed up in the email client. By switching to Zoho hosted mail I'd like to get away with email clients altogether. That's why frequent back up by the host (Zoho) is critical for me.

Thanks in advance for your input.