Why are Inbound emails with in-reply-to headers classified as NEW? - Support and Troubleshooting

Why are Inbound emails with in-reply-to headers classified as NEW? Description  The instance receives an inbound email which is a Reply to a previous email sent to the instance and which resulted in a record creation. The received email is classified as NEW even though it contains an in-reply-to header matching the messageID from the previous email received. Use case symptoms:

a) User 1 sends email to instance, and CC User 2 and User 3. Email is received in the instance, is classified as NEW, and incident INC0100001 is created. b) User 2 Reply to all on the email sent by User 1. Instance receives the replied email, but classifies it as NEW in spite of existent in-reply-to header which is already related to INC0100001. A new Incident INC0100002 is created. This result was not expected. d) User 3 Reply to all on the email sent by User 2. Instance receives the replied email, and classifies it as REPLY because the in-reply-to header related to INC0100002. The Incident INC0100002 is updated. This result is expected.

All reply emails sent:

have in-reply-to header have RE: prefix in subject do not have a Watermark do not have Record numbers

Cause The email sent by User 2 is classified as NEW because User 2, impersonated by the inbound action, does not have the privileges to access the existent record INC0100001 related to the in-reply-to header.

When a received email does not have watermark and record number, ServiceNow checks the email in-reply-to header. If the header contains a value that matches a previously received email message that resulted in a record creation, then the email is classified as a Reply to that record and the record is updated.

In the use case described above, User 2 does not have privileges to access INC0100001. Therefore, even though the instance has an Incident record related to the same MessageID, it is not found during the inbound action execution. Then, the received email is classified as NEW, and a new incident is created.

Keep in mind that all inbound actions run impersonating the user that sends the email to the instance, therefore all access and restrictions for that impersonated user will apply.

Resolution Provide the correct access to users that are authorized to interact via email.

Additional Information Ref. Inbound email actions:

https://docs.servicenow.com/csh?topicname=c_InboundEmailActions.html&version=latest