There is a somewhat common case where the "Collect WorkFlow Failure" service page begins to error out due to an "Improperly formatted email address" of a user in either the "WorkFlowFailureAll" or the "WorkFlowFailureByTargetAccess" security groups.
To a user of DSP, it makes sense to fix this problem by going to the Admin -> Security -> Users page and updating the NULL or invalid email address. However, after making such a change, the "Collect WorkFlow Failure" service page will go on failing until the offending records are removed from the DataGarage.dbo.dgSendWorkFlowFailure table. This necessitates a direct DELETE query on the table in SQL, filtering on the NULL or invalid email addresses.
Options for a simpler fix:
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