Summary
Some customer email systems can send SN instances multiple emails with the same Message-ID. By default the instance will save the first email into the [sys_email] table, and then silently drop any subsequent ones with the same Message ID.
2020-01-22 10:07:06 (056) worker.5 worker.5 txid=12f345bc1ba6 Message UID='00123f4e56789745' Message-ID='<AJGHEYTISMBTHAYAAAAAAAAAMEul/ioeqdYUIO1jyq7tY3CgAAAEAAAAICPx8Ch0U1Bu2IX+wLq2D0BBBBB==@example.com>' was previously read and will be ignored.
2023-02-20 04:23:21 (041) worker.2 worker.2 txid=203c7c30dgds Message UID='01475aef57822l4p' Message-ID='<AJGHEYTISMBTHAYAAAAAAAAAMEul/ioeqdYUIO1jyq7tY3CgAAAEAAAAICPx8Ch0U1Bu2IX+wLq2D0BBBBB==@example.com>' was previously read (sys_id of email='684cbc30dbcd29d051f961bb139665b3') and will be ignored
Release
All current ServiceNow versions
Instructions
The default behaviour can be changed by setting the system property glide.email.allow_duplicate_message_ids (of type true|false) to the value true.
This change has implications, in particular that matching of reply emails based on the In-Reply-To header will pick up a random email from the duplicates.
Related Links
The ServiceNow platform by default assumes that Message IDs are unique. Ref. 3.6.4. Identification Fields in relevant specification https://tools.ietf.org/html/rfc5322#section-3.6.4 :