Renaming Emails

I have a situation where I have to rename several users emails.  We had used, in the past, generic email addresses such as:
help@domain.com.  

Now we, because of new CRM software etc., we want to change those to an actual name
fred@domain.com.

I want to do this without losing any of the previous emails and use "help@domain.com" as an alias for "fred@domain.com.

Since we are using a hybrid system with Office 365 and Azure, I'm looking for the easiest and safest way to do this.

The user logins for the workstations are the same as the email address, ie "help", so I know I'm going to have to assign new user logins.
I assume I will also have to add a new account to Outlook.

I know that I have left some things out so any ideas would be a big help


Thanks
Kenbg