[5.3] Support custom recipient(s) with MailMessage

[tillkruss]

This comes in handy when sending "email address confirmation" requests.

[spyric]

Why don't you want to add routeNotificationForMail function to your Notifiable model?

[tillkruss]

It's quite an effort to override the returned email address of routeNotificationForMail() and just calling to() when needed is much easier.

[taylorotwell]

Aren't you sending to a user object? I still don't understand why using the email address on the user object wouldn't work fine?

[tillkruss]

I often encounter this workflow:

• The user has an email address: john@doe.com
• The user changes his email address to: johndoe@example.com
• The email address in the users table remains as john@doe.com until the user opens the link that has been sent to johndoe@example.com

Using routeNotificationForMail() on the Notifiable object doesn't allow me to send a notification to the "unverified" email address, only to the current one.