This issue occurs when the SMTP address of a Mail-In database is a member of a distribution list and a custom filtering rule is configured to filter on the related distribution list. The result is that actions associated with the custom filtering rule are not performed.
To work around this issue perform the following:
Add the SMTP address of the mail-in database to desired rule.
<RULE NAME="Benefits correspondence" ACTION="MARK_DO_NOT_ARCHIVE">
This issue has been addressed as part of the following release:
Enterprise Vault 9.0.1 - Release Details
Enterprise Vault 10.0 - Release Details