Add the ability to override the fallback email

[abdullah-kasim]

Description

Changelog Description

Pre-review checklist

Please make sure the items below have been covered before requesting a review:

• [ ] This change works and has been tested locally (or has an appropriate fallback).
• [ ] This change works and has been tested on a Go sandbox.
• [ ] This change has relevant unit tests (if applicable).
• [ ] This change uses a rollout method to ease with deployment (if applicable - especially for large scale actions that require writes).
• [ ] This change has relevant documentation additions / updates (if applicable).
• [ ] I've created a changelog description that aligns with the provided examples.

Pre-deploy checklist

• [ ] VIP staff: Ensure any alerts added/updated conform to internal standards (see internal documentation).

Steps to Test