mail/internal/mail/message.go
func SetCopyFunc(f func(io.Writer) error) FileSetting {
	return func(fi *file) {
		fi.CopyFunc = f
	}
}
func SetCopyFunc(f func(io.Writer) error) FileSetting {
	return func(fi *file) {
		fi.CopyFunc = f
	}
}
func SetCopyFunc ( f func ( io . Writer ) error ) FileSetting { return func ( fi * file ) { fi . CopyFunc = f } }
// SetCopyFunc is a file setting to replace the function that runs when the
// message is sent. It should copy the content of the file to the io.Writer.
//
// The default copy function opens the file with the given filename, and copy
// its content to the io.Writer.
SetCopyFunc is a file setting to replace the function that runs when the message is sent . It should copy the content of the file to the io . Writer . The default copy function opens the file with the given filename and copy its content to the io . Writer .