Passwordless Scenario Where Email Send Fails to Reach Requester

My authentication with Auth0 passwordless has worked well but I have a scenario that comes up on occasion with one of my clients.

  1. User inputs email address which we check against a Salesforce integration
  2. Success w/ Salesforce, we then hit the Auth0 JS API with a request for the passwordless code to be delivered via email
  3. Success w/ Auth0, triggers our email provider AWS SES to send Auth0 code
  4. User never receives code (most likely because of tight spam filters, many corporate users in my app)

So my question is…what do we do? Normally, this turns into a support hassle, where user is frustrated about never getting code and we have to haggle around with a 3rd party corporate IT email spam thing. What would be great is if we could give our users a second path via phone:

Amendment to process above:
3b) User never receives code and is offered the opportunity to input their phone to get a code mailed to them (needs to work for intl numbers).

Is this possible?