Send email from backup SMTP server based on sending address

It would be handy if we could send between the two SMTP servers based on a whitelist. For example, if email is being sent to [email protected], or anything at *@example.com, then use the secondary server for sending.

We use SES primarily for user transactional and marketing emails; we also have our own mail server that we use for internal purposes, and send from that when we use internal addresses (the emails are also connected to different software outside of WordPress).

I understand it may not be a use case everyone would need, but maybe it’d make a good extension for the plugin. Just dropping a recommendation in here. Or if anyone knows of a way of doing this, I’d be interested in hearing that.