This may occur due to any of the following:

• The emails are listed in the RBL+/QIL database and were blocked by HES.
• A firewall policy is restricting access from HES / HES - Inbound Filtering servers.
• HES servers are not sending to the correct receiving MTA of the customer.

To resolve the issue, do one of the following:

• Check the mail tracking logs of HES:
  1. Log in to the HES console.
  2. Go to Logs > Mail Tracking.

  3. Select the date range.

      

     Only the emails from the last seven (7) days and last thirty (30) days on HES 2.0 can be tracked, and data from the last two (2) hours may not be displayed yet.

  4. Specify the sender of the missing email.

     

     Click image to enlarge.

  5. Check if the sender is listed in the Accepted Traffic or the Blocked Traffic tab, and do one of the following:

     • If it is listed under Accepted Traffic, proceed to checking the firewall policies.

     • If it is listed under Blocked Traffic and you are sure the sender can be trusted, you can opt to add it to the Approved Senders list.

• Check if a firewall ACL is blocking/dropping traffic from HES / HES - Inbound Filtering servers. Make sure that the ACL of the domain is accepting emails from the IP addresses of the HES/HES – Inbound Filtering IP mail servers.
  
   

  If you need assistance, contact your network administrator.
• If all emails are not being received, see if you have made any changes to the IP addresses of your domain registered with HES / HES - Inbound Filtering. If so, contact Trend Micro Technical Support so that we may update our records and forward the emails correctly.