You will usually find the distribution box buried a few feet underground, close to your septic tank or at the edge of your drain field. Start by looking for any visible access lids in these areas. When it fails, symptoms include uneven wet spots in the yard, slow indoor drains, and sewage odors. Knowing how to inspect and test a septic distribution box can help catch problems early and. Info I found online indicates she could be just "mailbox" so I tried to fix the filters. I used this command to "fix" the filters: Set-DynamicDistributionGroup -Identity ******@contoso. Always use caution and look for. Diagnose problems at the septic system drop box: procedures for troubleshooting leaks, smells, or backups & flooding in the septic system D-box.