Is your feature request related to a problem? Please describe.
For sending mfa code emails in a multi Site setup. we need to be able to send mails with more context data, like site.name. The current implementation does not pass the request object to the backend which makes it impossible to use the request in rendering the email templates.

Describe the solution you'd like
Pass the request object to the backend. Allow for implementing get_context in subclass. Pass the extra context to the template rendering.

Describe alternatives you've considered
Write a separate backend for each site.

Additional context
None