Why do incident responses fail to send an e-mail while forward works correctly?

Environment:

Oracle B2C Service Incident Emails, Message Templates

Issue:

 Incident responses are not being emailed to customers when clicking "Send" or "Send & Close" (BUI or .NET), or using "Send On Save" (.NET only).   The Audit log is missing "Response Sent" or showing "Failure -  Message delivery to some recipients failed".  Incidents being forwarded by email are working correctly.

Resolution:

There are several reasons why Incident Responses might not be emailed to the contact.  One possibility is that Message Templates for Contact Emails for Incidents may not be configured to send.   

Configure Contact Message Templates to send:

1. Navigate to Configuration > Site Configuration > Message Templates
2. Click the Interface
3. On the ribbon, click Contact Emails and expand the Incident drop-down menu
4. The check boxes must be selected for the corresponding Message Template to send
5. On the ribbon, click Deploy All and Save & Close

Another reason an email might not be sent is if the incident hits a business rule with action "Do Not Send Response". To troubleshoot this cause, check the Rule Log  (Legacy business rules in .NET) or Rule Runtime Log (Browser UI Enhanced Business Rules) for all rules hit and look for rules with "Do Not Send Response" actions:

Answer ID 11881: Accessing the "Rule Runtime Log" for Enhanced Business Rules in Browser UI 
Answer ID 1873: Using the Rule Log to troubleshoot rules 
Answer ID 551: Actions a business rule can execute
 

Additional reasons may include incorrect outgoing mailbox configurations or smtp delivery failures. Delivery failures will typically be bounced by receiving mail servers, so it is generally recommended to enable the EGW_SAVE_EMAIL_HEADERS configuration in order to capture delivery information regarding failed addresses. Your site can be configured to allow returned messages into the system which gives you the opportunity to review the message and and attempt to find root cause of the failure. Alternatively, you can configure your mailboxes to send rejected messages to a different email address without having them create or update existing incidents. Please see the below link regarding applicable mailbox configurations:

Answer ID 1638: Allowing bounced incident responses into Oracle B2C Service for review

Depending on the source of the failure, additional information may be found in the transactions table (trans_type 15 (Failure) & transactions.description). These fields have full analytics usage. Please see  Answer ID 11957: Reporting and Troubleshooting for "Message Delivery to Some Recipients Failed" Audit Log failures  regarding possible values for attribute and description fields within the transactions table.