code: public void addMailHost(String hostname, String order, String protocol, String username, String password) {
  
          addMailHost(hostname, "25", order, protocol, null, username, password);
      }
docs: Adds a new mail host to the internal list of mail hosts with default port 25.<p>
  
  @param hostname the name of the mail host
  @param order the order in which the host is tried
  @param protocol the protocol to use (default "smtp")
  @param username the user name to use for authentication
  @param password the password to use for authentication