发送营销电子邮件时我的帐户被阻止

我目前正在创建营销电子邮件，打算向个人客户发送个性化的批量电子邮件。 但是，如果某些电子邮件地址碰巧不存在，那么当这些电子邮件退回时，我的 MS Office 365 帐户就有被阻止的风险。

如何避免这个问题，这个应用程序用于批量电子邮件拍摄。

弹跳后的错误：
在 abc.com 上找不到 someemail@abc.com

我尝试过的：

MailMessage msg = new MailMessage();
            msg.To.Add(new MailAddress(toEmail, recipientName));
            msg.From = new MailAddress(fromEmail, emailConfig.DisplayName);
            msg.Subject = emailSub;
            emailBody = emailBody.Replace("[Name]", recipientName);
            msg.Body = emailBody;
            //attachments//
            var lst = getTemplateAttachments(templateId);
            foreach (var item in lst)
            {
                byte[] bytes = File.ReadAllBytes(item.FilePath);
                MemoryStream ms = new MemoryStream(bytes);
                Attachment data = new Attachment(ms, item.FileName);
                msg.Attachments.Add(data);

            }

            //attachments//
            msg.IsBodyHtml = true;
            msg.BodyEncoding = System.Text.Encoding.UTF8;
            SmtpClient smtpclient = new SmtpClient();
            smtpclient.UseDefaultCredentials = true;
            smtpclient.Credentials = new System.Net.NetworkCredential(emailConfig.FromEmail, emailConfig.Password);
           
            smtpclient.Port = 587; 
            smtpclient.Host = "smtp.office365.com";
           
            smtpclient.DeliveryMethod = SmtpDeliveryMethod.Network;
            smtpclient.EnableSsl = true;
            
            try
            {
                
                smtpclient.Send(msg);
               
                resp.IsSent = true;
                resp.RespMsg = "success";
                return resp;


            }
            catch (Exception ex)
            {}