code: def sendEmail(self, emails, massType='SingleEmailMessage'):
          
          return SendEmailRequest(
              self.__serverUrl,
              self.sessionId,
              emails,
              massType
          ).post(self.__conn)
docs: Send one or more emails from Salesforce.
  
          Parameters:
              emails - a dictionary or list of dictionaries, each representing a
                       single email as described by https://www.salesforce.com/us
                       /developer/docs/api/Content/sforce_api_calls_sendemail.htm
              massType - 'SingleEmailMessage' or 'MassEmailMessage'.
                         MassEmailMessage is used for mailmerge of up to 250
                         recepients in a single pass.
  
          Note:
              Newly created Salesforce Sandboxes default to System email only. In
              this situation, sendEmail() will fail with NO_MASS_MAIL_PERMISSION.