Maybe someone knows the best way to create email. mail via code (api, etc)?

Question

API

It is necessary that the application itself skillfully create mail on demand.

Answer 1

If you are considering your own server, then for example, the postfix + dovecot bundle can take data about mailboxes from a database, for example, mysql. Or from files of a rather simple format.
Writing an application that will implement the API for working with boxes is not a difficult task, just like working directly with the database of boxes from your application.

Answer 2

Extra quotes when calling .css()
Instead , '"visibility", "hidden"'try "visibility", "hidden". Same for visible.
And what is .kirpi4i()?

Answer 3

$( '.container' ).css("visibility", "hidden" )
                 .kirpi4i()
                 .css( "visibility", "visible");

If kirpi4i()it's a feature and not a plugin, then remove it.