code: @Nonnull
    public ESuccess queueMail (@Nonnull final ISMTPSettings aSMTPSettings, @Nonnull final IMutableEmailData aMailData)
    {
      return MailAPI.queueMail (aSMTPSettings, aMailData);
    }
docs: Unconditionally queue a mail
  
  @param aSMTPSettings
  The SMTP settings to use. May not be <code>null</code>.
  @param aMailData
  The data of the email to be send. May not be <code>null</code>.
  @return {@link ESuccess}