fix AF-2749
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
* **New Features**
* Added support for configuring a fallback SMTP server for outgoing
emails.
* Introduced the ability to specify email domains that will always use
the fallback SMTP server.
* Enhanced email sending to automatically route messages to the
appropriate SMTP server based on recipient domain.
* **Documentation**
* Updated configuration options and descriptions in the admin interface
to reflect new fallback SMTP settings.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
61fa3ef6f6