Binary package “masqmail” in ubuntu xenial

mail transport agent for intermittently connected hosts

 Masqmail is an MTA (mail transport agent) for hosts with no
 permanent network connection, such as home network servers or
 notebook computers. It has special support for connections to
 different Internet Service Providers.
 In these cases, Masqmail is a slim replacement for full-blown MTAs
 such as Sendmail, Exim, Qmail or Postfix.