Multi-language design found in mail m_db' incorrectly causing valid target mail files, that are not multi-language, to NOT be archived.
Event ID 41162 - Error: Multi-language design found in mail m_db [EVDG/SYMC!!mail\User.nsf]
If the ICON Note was present in the mail file but did not contain the $LANGUAGE field, then archive processing would fail for that mailbox.
This issue has been addressed as part of the following release:
Enterprise Vault 9.0.3 - Release Details
Enterprise Vault 10.0.1 - Release Details