Although it is possible to avoid this issue by configuring ESET Mail Security for Microsoft Exchange Server to delete all emails marked as spam, the drawback of this method is that if a legitimate email is deleted, it cannot be restored locally.
Use the solution below to create a Transport rule in Microsoft Exchange that will effectively apply a policy that redirects emails with null sender addresses to a specified quarantine mailbox. The use of this method allows you to restore a legitimate message in the event that it is incorrectly flagged as spam.
6. Specify the actions for your new rule:
7. Specify the Exceptions for your new rule. We recommend that you create exceptions to exclude the text patterns used in out-of-office emails, non-delivery reports (NDRs) and/or delivery status notifications (DSNs) to keep these messages from being quarantined even though they use a null sender address. To do so, follow the instructions below: