Simple Email Forwarder Application

I need to build a very simple email forwarder application. I need a front-end to create and manage email accounts. The application should be secure and mobile friendly. Use case, I want on the front end to input First Name, Last Name, and an optional recovery email address as well as optional notes/description. This could all be stored in a json file or some simple solution we read on load. A DB works too but little more management overhead. On the backend, I need it to create an email address forwarder that forwards always to email @ company.com and if the optional recovery email is defined, there as well. For Example. Front end technician types in First: Bob Last: Smith Recovery Email: test @ abc.com Notes: Bob over on 73rd It creates an email address of bsmith (or bsmith1 if bsmith is already taken)@ clients.company.com This would then allow us to receive emails at that address (by forwarding them to the static email, as well as the client email defined) We would want this page authenticated and of course all the items XSS resistant. The backend the accounts are actually created in and receiving/forwarding can be M365 or a local SMTP. Bonus but not required: All front-end management is done inside Slack App. Im not stuck on this so I dont really care but would be cool