Skip to main content


8x8 Support

Contact Center Emails Delayed or Not Received


Why are emails sent from cases not delivered or delayed?

Applies To

  • Contact Center
  • Cases
  • MailSend Process
  • SMTP
  • Public Internet 
  • Destination Inboxes


There are instances where there is a significant delay in the mail send process and at time not responding. Emails are not guaranteed to be delivered in any particular timeframe and delays can be attributable to a number of things;

  1. There is a long queue of outbound emails to send from our MAILSND process.
  2. The supplied SMTP endpoint is slow or unresponsive.
  3. The public internet injects delays.
  4. The MAILSD process has choked and needs re-booting.

Reasons 1 to 3 normally equate to minutes not hours and Attributes to delays in the email.

Reason 4 can result in the destination not receiving emails this is noticed by alarms in the infrastructure monitoring and can take several hours before it is noticed and we don't always notice that the service is unresponsive so it can take a while before it gets manually rebooted or we clear the specific email in the queue (this process often entails tracking down the email that is choking the system which then needs to be quarantined, before the system can be rebooted) and reboot the service.

Additional Information

This is usually only noticed when an email recipient reports they have not received an email, further to this testing of the email SMTP Settings if using custom Configuration can show successful connection and although the test emails are sent and received the work flow of the tests do differ and emails are sent directly to SMTP hosts to send the email and does not flow through the same mail send process. checking the test SMTP connection does not reflect this and does require further checks on the email parser and an engineering ticket is required to reboot the service manually.