private async Task ProcessBlast(Template template, Customer customer, List <EmailRecipient> recipients, CancellationToken cancellationToken)
        {
            foreach (var recipient in recipients)
            {
                if (recipient.Email == null)
                {
                    _logger.LogWarning($"Could not deliver email to recipient {recipient.Name}: no email address");
                    continue;
                }

                var mailMessage = new MailMessage("*****@*****.**", recipient.Email)
                {
                    Body       = await _templateEngine.MergeTemplate(template, customer, recipient, cancellationToken),
                    IsBodyHtml = true
                };

                await _smtpClient.SendMailAsync(mailMessage);
            }
        }