Enable Email-Forwarding for outgoing emails

I have recently started using Zoho Mail for my organisation.
From the admin control-panel I have created some users for my organisation

Since all outgoing & incoming emails on company's email id is company's property, I want to forward both these emails to an external Gmail account for backup / monitoring purposes (I want to add this feature while creating the user in admin control-panel & user should not be able to change/delete them.)

Using https://www.zoho.com/mail/help/email-forwarding.html , I have enabled forwarding for incoming emails.
I will be grateful if someone could tell me how to forward all outgoing mails (any email sent by any user from my organisation) to a Gmail account.