Mailbox Junk Configuration
Mailbox Junk Configuration allows you to view and manage settings relevant to Junk Email configuration for individual mailboxes. Exchange settings at the mailbox level include enabling or disabling anti-spam filtering, custom SCL thresholds for Delete, Reject, Quarantine and Junk actions, and individual lists of allowed and blocked sender addresses and domains.
Many of these settings can be configured by users in Outlook Web App, however they are not otherwise visible or editable by Exchange administrators except via PowerShell. In troubleshooting or investigation scenarios, having visibility of the individual mailbox settings is critical as they can override organization- or server-level filtering rules.
Mailboxes must have been signed into at least once using Outlook or Outlook Web App
A mailbox must have been signed into using Outlook or Outlook Web Access before junk email configuration can be updated. You will receive an error if you try to update the junk email configuration for a newly-created mailbox which has never been signed into.
Mailbox Junk Configuration
This setting determines whether mailbox-level anti-spam settings (the Allowed & Blocked Senders and Domains lists, SCL Actions and Trust settings) are enabled. If this is disabled, all other mailbox-level anti-spam settings (except Anti-Spam Bypass) will be ignored.
This setting is configurable by the user in Outlook Web App using the setting Automatically filter junk email in the Block or allow section. By default anti-spam is enabled for each mailbox.
If this setting is disabled, organization- and server-level policies will still be applied. If troubleshooting false positives in a user's Junk Email folder, note that Outlook can also be set to perform client-side filtering which can move messages into the Junk Email folder. The Outlook client-side filtering is no longer recommended as it relies on SmartScreen definitions which are no longer updated.
This setting will cause virtually all organization- and server-level anti-spam policies to be bypassed for messages sent to this mailbox. The Anti-Spam Bypass setting is configurable only by Exchange administrators (it is not configurable in Outlook or Outlook Web App).
This setting determines whether contacts in the Contacts folder for the mailbox are treated as trusted senders (equivalent to being added to the Allowed Senders and Domains list).
This setting is configurable by the user in Outlook Web App using the setting Trust email from my contacts in the Block or allow section. By default, contacts are not automatically trusted.
Trusted Lists Only
If this setting is enabled, all messages except from an address in the Allowed Senders and Domains list will be delivered to the Junk Email folder instead of the Inbox. Note that it does not cause messages to be rejected or deleted.
This setting is configurable by the user in Outlook Web App using the setting Don't trust email unless it comes from someone in my Safe Senders and Recipients listin the Block or allow section.
Spam Confidence Level (SCL) Actions
If these actions are enabled, the action will be taken for messages which meet or exceed the specified SCL value. In the case of the SCL Junk Threshold, messages which meet (but to not necessarily exceed) the specified SCL value will be moved to the Junk Email folder. If configured, these mailbox-level values take precedence over the SCL values set for the Content Filter at the organization-level.
None of the SCL settings are visible to or configurable by users via Outlook or Outlook Web App.
Blocked Senders & Domains
Messages from sender addresses added to this list will be delivered to the Junk Email folder instead of the Inbox. Note that this list does not cause messages to be rejected or deleted.
This setting is configurable by the user in Outlook Web App using the list Blocked Senders in the Block or allow section.
Allowed Senders & Domains
Messages from sender addresses added to this list will never be delivered to the Junk Email folder.
This setting is configurable by the user in Outlook Web App using the list Safe Senders and Recipients in the Block or allow section.