We have more than 300 email accounts in the TO address field on 'Send Notification' task. We have received the following error message for the Send Notification.
Failed to send email
System.Net.Mail.SmtpException: The operation has timed out.
at System.Net.Mail.SmtpClient.Send(MailMessage message)
at Nintex.Workflow.HumanApproval.Message.SendEmail(String subject, User user, NWContext context, NWContextDataCollection ctxData, MailAddressCollection toAddresses)