salesforce 外部系统restful api方式集成sf邮件

                EmailMessage objEmail = new EmailMessage();
                objEmail.guid__c = RepostReq.EmailId;
                //email from address value
                objEmail.FromAddress = repostReq.fromAddress;
                //email from name value
                objEmail.FromName = repostReq.fromName;
                //email text body value
                objEmail.TextBody = repostReq.plainTextBody;
                //email html body value
                //objEmail.htmlBody = repostReq.htmlBody;
                //email subject value
                objEmail.Subject = repostReq.Subject;
                objEmail.RelatedToId = repostReq.recordidList[0];
                objEmail.status = '1';
                insert objEmail;


                for (Id RelationId : RelationIdList) {
                    EmailMessageRelation emlR = new EmailmessageRelation(EmailMessageId = objEmail.Id, 
                    RelationId = RelationId, // lead Id with a correctly formatted email address
                    RelationType = 'ToAddress');
                    insert emlR;
                }