Load default values from file config (services.php / .env)

[matteotrubini]

No description provided.

[LukeTowers]

Why is this required? It could represent unintentional disclosure of secrets and shouldn't be required with how the mail configuration flow works.

[matteotrubini]

This replicates the behavior of the SMTP configuration where auth fields are initially populated and shown from config.
As auth details are required fields, pre-populate them prevent to re-insert credential any time you change only sender data.

I agree on the disclosure problem, but in that case I think also SMTP password should be hidden.

A solution could be to populate the username field (to show which auth data is currently configured on the system), but not the password, skipping blank password on save.

[LukeTowers]

Hmm, fair points. I suppose the settings are already protected behind system.manage_mail_settings assigned to the Developer role only by default so it should be fine to allow this. Does setting the defaults like this PR does work currently? I know default values aren't used if you aren't in a create context or if the form's record already exists.

[matteotrubini]

Based on my usage if record in table doesn't exists (like when you "reset to default") default values are loaded, else current ones saved on DB are shown.

You can accept this PR and plan to implement the "skip on blank" strategy for passwords / keys (maybe via filterFields() ?)

[LukeTowers]

@bennothommo any thoughts?