@startuml

abstract SmtpServerModelABC {
  host : CharField
  host_user : CharField
  is_active : BooleanField
  is_auth_required : BooleanField
  outbound_email : EmailField
  password : CharField
  port : IntegerField
  security_protocol : CharField
  ssl_cert_file : FileField
  ssl_key_file : FileField
  updated_at : DateTimeField
  use_certificate : BooleanField
}

abstract SingletonModel {

}

class SmtpLocalServer {

}
SmtpServerModelABC <|-- SmtpLocalServer
SingletonModel <|-- SmtpLocalServer

class SmtpCorporateServer {

}
SmtpServerModelABC <|-- SmtpCorporateServer
SingletonModel <|-- SmtpCorporateServer
@enduml