Recommended settings for EOP and Microsoft Defender for Office 365 security

Tip

Did you know you can try the features in Microsoft 365 Defender for Office 365 Plan 2 for free? Use the 90-day Defender for Office 365 trial at the Microsoft 365 Defender portal trials hub. Learn about who can sign up and trial terms here.

Applies to

• Exchange Online Protection
• Microsoft Defender for Office 365 plan 1 and plan 2
• Microsoft 365 Defender

Exchange Online Protection (EOP) is the core of security for Microsoft 365 subscriptions and helps keep malicious emails from reaching your employee's inboxes. But with new, more sophisticated attacks emerging every day, improved protections are often required. Microsoft Defender for Office 365 Plan 1 or Plan 2 contain additional features that give admins more layers of security, control, and investigation.

Although we empower security administrators to customize their security settings, there are two security levels in EOP and Microsoft Defender for Office 365 that we recommend: Standard and Strict. Although customer environments and needs are different, these levels of filtering will help prevent unwanted mail from reaching your employees' Inbox in most situations.

To automatically apply the Standard or Strict settings to users, see Preset security policies in EOP and Microsoft Defender for Office 365.

This article describes the default settings, and also the recommended Standard and Strict settings to help protect your users. The tables contain the settings in the Microsoft 365 Defender portal and PowerShell (Exchange Online PowerShell or standalone Exchange Online Protection PowerShell for organizations without Exchange Online mailboxes).

Note

The Office 365 Advanced Threat Protection Recommended Configuration Analyzer (ORCA) module for PowerShell can help you (admins) find the current values of these settings. Specifically, the Get-ORCAReport cmdlet generates an assessment of anti-spam, anti-phishing, and other message hygiene settings. You can download the ORCA module at https://www.powershellgallery.com/packages/ORCA/.

In Microsoft 365 organizations, we recommend that you leave the Junk Email Filter in Outlook set to No automatic filtering to prevent unnecessary conflicts (both positive and negative) with the spam filtering verdicts from EOP. For more information, see the following articles:

• Configure junk email settings on Exchange Online mailboxes
• About junk email settings in Outlook
• Change the level of protection in the Junk Email Filter
• Create safe sender lists in EOP
• Create blocked sender lists in EOP

Anti-spam, anti-malware, and anti-phishing protection in EOP

Anti-spam, anti-malware, and anti-phishing are EOP features that can be configured by admins. We recommend the following Standard or Strict configurations.

EOP anti-spam policy settings

To create and configure anti-spam policies, see Configure anti-spam policies in EOP.

Wherever you select Quarantine message as the action for a spam filter verdict, a Select quarantine policy box is available. Quarantine policies define what users are able to do to quarantined messages, and whether users receive quarantine notifications. For more information, see Anatomy of a quarantine policy.

If you change the action of a spam filtering verdict to Quarantine message when you create anti-spam policies the the Defender portal, the Select quarantine policy box is blank by default. A blank value means the default quarantine policy for that spam filtering verdict is used. These default quarantine policies enforce the historical capabilities for the spam filter verdict that quarantined the message as described in the table here. When you later view or edit the anti-spam policy settings, the quarantine policy name is shown.

Admins can create or use quarantine policies with more restrictive or less restrictive capabilities. For instructions, see Create quarantine policies in the Microsoft 365 Defender portal.

Security feature name	Default	Standard	Strict	Comment
Bulk email threshold & spam properties
Bulk email threshold BulkThreshold	7	6	5	For details, see Bulk complaint level (BCL) in EOP.
MarkAsSpamBulkMail	On	On	On	This setting is only available in PowerShell.
Increase spam score settings	Off	Off	Off	All of these settings are part of the Advanced Spam Filter (ASF). For more information, see the ASF settings in anti-spam policies section in this article.
Mark as spam settings	Off	Off	Off	Most of these settings are part of ASF. For more information, see the ASF settings in anti-spam policies section in this article.
Contains specific languages EnableLanguageBlockList LanguageBlockList	Off $false Blank	Off $false Blank	Off $false Blank	We have no specific recommendation for this setting. You can block messages in specific languages based on your business needs.
From these countries EnableRegionBlockList RegionBlockList	Off $false Blank	Off $false Blank	Off $false Blank	We have no specific recommendation for this setting. You can block messages from specific countries based on your business needs.
Test mode (TestModeAction)	None	None	None	This setting is part of ASF. For more information, see the ASF settings in anti-spam policies section in this article.
Actions
Spam detection action SpamAction	Move message to Junk Email folder MoveToJmf	Move message to Junk Email folder MoveToJmf	Quarantine message Quarantine
Quarantine policy for Spam SpamQuarantineTag	DefaultFullAccessPolicy¹	DefaultFullAccessPolicy	DefaultFullAccessWithNotificationPolicy	The quarantine policy is meaningful only if spam detections are quarantined.
High confidence spam detection action HighConfidenceSpamAction	Move message to Junk Email folder MoveToJmf	Quarantine message Quarantine	Quarantine message Quarantine
Quarantine policy for Hight confidence spam HighConfidenceSpamQuarantineTag	DefaultFullAccessPolicy¹	DefaultFullAccessWithNotificationPolicy	DefaultFullAccessWithNotificationPolicy	The quarantine policy is meaningful only if high confidence spam detections are quarantined.
Phishing detection action PhishSpamAction	Move message to Junk Email folder* MoveToJmf	Quarantine message Quarantine	Quarantine message Quarantine	* The default value is Move message to Junk Email folder in the default anti-spam policy and in new anti-spam policies that you create in PowerShell. The default value is Quarantine message in new anti-spam policies that you create in the Microsoft 365 Defender portal.
Quarantine policy for Phishing PhishQuarantineTag	DefaultFullAccessPolicy¹	DefaultFullAccessWithNotificationPolicy	DefaultFullAccessWithNotificationPolicy	The quarantine policy is meaningful only if phishing detections are quarantined.
High confidence phishing detection action HighConfidencePhishAction	Quarantine message Quarantine	Quarantine message Quarantine	Quarantine message Quarantine	Users can't release their own messages that were quarantined as high confidence phishing, regardless of how the quarantine policy is configured. If the policy allows users to release their own quarantined messages, users are instead allowed to request the release of their quarantined high-confidence phishing messages.
Quarantine policy for High confidence phishing HighConfidencePhishQuarantineTag	AdminOnlyAccessPolicy	AdminOnlyAccessPolicy	AdminOnlyAccessPolicy
Bulk detection action BulkSpamAction	Move message to Junk Email folder MoveToJmf	Move message to Junk Email folder MoveToJmf	Quarantine message Quarantine
Quarantine policy for Bulk BulkQuarantineTag	DefaultFullAccessPolicy¹	DefaultFullAccessPolicy	DefaultFullAccessWithNotificationPolicy	The quarantine policy is meaningful only if bulk detections are quarantined.
Retain spam in quarantine for this many days QuarantineRetentionPeriod	15 days	30 days	30 days	This value also affects messages that are quarantined by anti-phishing policies. For more information, see Quarantined email messages in EOP.
Enable spam safety tips InlineSafetyTipsEnabled	Selected $true	Selected $true	Selected $true
Enable zero-hour auto purge (ZAP) for phishing messages PhishZapEnabled	Selected $true	Selected $true	Selected $true
Enable ZAP for spam messages SpamZapEnabled	Selected $true	Selected $true	Selected $true
Allow & block list
Allowed senders AllowedSenders	None	None	None
Allowed sender domains AllowedSenderDomains	None	None	None	Adding domains to the allowed senders list is a very bad idea. Attackers would be able to send you email that would otherwise be filtered out. Use the spoof intelligence insight and the Tenant Allow/Block List to review all senders who are spoofing sender email addresses in your organization's email domains or spoofing sender email addresses in external domains.
Blocked senders BlockedSenders	None	None	None
Blocked sender domains BlockedSenderDomains	None	None	None

¹ As described in Full access permissions and quarantine notifications, your organization might use NotificationEnabledPolicy instead of DefaultFullAccessPolicy in the default security policy or in new custom security policies that you create. The only difference between these two quarantine policies is quarantine notifications are turned on in NotificationEnabledPolicy and turned off in DefaultFullAccessPolicy.

ASF settings in anti-spam policies

For more information about Advanced Spam Filter (ASF) settings in anti-spam policies, see Advanced Spam Filter (ASF) settings in EOP.

Security feature name	Default	Recommended Standard	Recommended Strict	Comment
Image links to remote sites IncreaseScoreWithImageLinks	Off	Off	Off
Numeric IP address in URL IncreaseScoreWithNumericIps	Off	Off	Off
URL redirect to other port IncreaseScoreWithRedirectToOtherPort	Off	Off	Off
Links to .biz or .info websites IncreaseScoreWithBizOrInfoUrls	Off	Off	Off
Empty messages MarkAsSpamEmptyMessages	Off	Off	Off
Embed tags in HTML MarkAsSpamEmbedTagsInHtml	Off	Off	Off
JavaScript or VBScript in HTML MarkAsSpamJavaScriptInHtml	Off	Off	Off
Form tags in HTML MarkAsSpamFormTagsInHtml	Off	Off	Off
Frame or iframe tags in HTML MarkAsSpamFramesInHtml	Off	Off	Off
Web bugs in HTML MarkAsSpamWebBugsInHtml	Off	Off	Off
Object tags in HTML MarkAsSpamObjectTagsInHtml	Off	Off	Off
Sensitive words MarkAsSpamSensitiveWordList	Off	Off	Off
SPF record: hard fail MarkAsSpamSpfRecordHardFail	Off	Off	Off
Sender ID filtering hard fail MarkAsSpamFromAddressAuthFail	Off	Off	Off
Backscatter MarkAsSpamNdrBackscatter	Off	Off	Off
Test mode TestModeAction)	None	None	None	For ASF settings that support Test as an action, you can configure the test mode action to None, Add default X-Header text, or Send Bcc message (None, AddXHeader, or BccMessage). For more information, see Enable, disable, or test ASF settings.

Note

ASF adds X-CustomSpam: X-header fields to messages after the messages have been processed by Exchange mail flow rules (also known as transport rules), so you can't use mail flow rules to identify and act on messages that were filtered by ASF.

EOP outbound spam policy settings

To create and configure outbound spam policies, see Configure outbound spam filtering in EOP.

For more information about the default sending limits in the service, see Sending limits.

Note

Outbound spam policies are not part of Standard or Strict preset security policies. The Standard and Strict values indicate our recommended values in the default outbound spam policy or custom outbound spam policies that you create.

Security feature name	Default	Recommended Standard	Recommended Strict	Comment
Set an external message limit RecipientLimitExternalPerHour	0	500	400	The default value 0 means use the service defaults.
Set an internal message limit RecipientLimitInternalPerHour	0	1000	800	The default value 0 means use the service defaults.
Set a daily message limit RecipientLimitPerDay	0	1000	800	The default value 0 means use the service defaults.
Restriction placed on users who reach the message limit ActionWhenThresholdReached	Restrict the user from sending mail until the following day BlockUserForToday	Restrict the user from sending mail BlockUser	Restrict the user from sending mail BlockUser
Automatic forwarding rules AutoForwardingMode	Automatic - System-controlled Automatic	Automatic - System-controlled Automatic	Automatic - System-controlled Automatic
Send a copy of outbound messages that exceed these limits to these users and groups BccSuspiciousOutboundMail BccSuspiciousOutboundAdditionalRecipients	Not selected $false Blank	Not selected $false Blank	Not selected $false Blank	We have no specific recommendation for this setting. This setting only works in the default outbound spam policy. It doesn't work in custom outbound spam policies that you create.
Notify these users and groups if a sender is blocked due to sending outbound spam NotifyOutboundSpam NotifyOutboundSpamRecipients	Not selected $false Blank	Not selected $false Blank	Not selected $false Blank	The default alert policy named User restricted from sending email already sends email notifications to members of the TenantAdmins (Global admins) group when users are blocked due to exceeding the limits in policy. We strongly recommend that you use the alert policy rather than this setting in the outbound spam policy to notify admins and other users. For instructions, see Verify the alert settings for restricted users.

EOP anti-malware policy settings

To create and configure anti-malware policies, see Configure anti-malware policies in EOP.

Quarantine policies define what users are able to do to quarantined messages, and whether users receive quarantine notifications. For more information, see Anatomy of a quarantine policy.

The policy named AdminOnlyAccessPolicy enforces the historical capabilities for messages that were quarantined as malware as described in the table here.

Users can't release their own messages that were quarantined as malware, regardless of how the quarantine policy is configured. If the policy allows users to release their own quarantined messages, users are instead allowed to request the release of their quarantined malware messages.

Security feature name	Default	Standard	Strict	Comment
Protection settings
Enable the common attachments filter EnableFileFilter	Selected $true*	Selected $true	Selected $true	For the list of file types in the common attachments filter, see Anti-malware policies. * The common attachments filter is on by default in new anti-malware policies that you create in the Microsoft 365 Defender portal. The common attachments filter is off by default in the default anti-malware policy and in new policies that you create in PowerShell.
Common attachment filter notifications (When these file types are found) FileTypeAction	Reject the message with a non-delivery report (NDR) Reject	Reject the message with a non-delivery report (NDR) Reject	Reject the message with a non-delivery report (NDR) Reject
Enable zero-hour auto purge for malware ZapEnabled	Selected $true	Selected $true	Selected $true
Quarantine policy QuarantineTag	AdminOnlyAccessPolicy	AdminOnlyAccessPolicy	AdminOnlyAccessPolicy
Admin notifications
Notify an admin about undelivered messages from internal senders EnableInternalSenderAdminNotifications InternalSenderAdminAddress	Not selected $false	Not selected $false	Not selected $false	We have no specific recommendation for this setting.
Notify an admin about undelivered messages from external senders EnableExternalSenderAdminNotifications ExternalSenderAdminAddress	Not selected $false	Not selected $false	Not selected $false	We have no specific recommendation for this setting.
Customize notifications				We have no specific recommendations for these settings.
Use customized notification text CustomNotifications	Not selected $false	Not selected $false	Not selected $false
From name CustomFromName	Blank $null	Blank $null	Blank $null
From address CustomFromAddress	Blank $null	Blank $null	Blank $null
Customize notifications for messages from internal senders				These settings are used only if Notify an admin about undelivered messages from internal senders is selected.
Subject CustomInternalSubject	Blank $null	Blank $null	Blank $null
Message CustomInternalBody	Blank $null	Blank $null	Blank $null
Customize notifications for messages from external senders				These settings are used only if Notify an admin about undelivered messages from external senders is selected.
Subject CustomExternalSubject	Blank $null	Blank $null	Blank $null
Message CustomExternalBody	Blank $null	Blank $null	Blank $null

EOP anti-phishing policy settings

For more information about these settings, see Spoof settings. To configure these settings, see Configure anti-phishing policies in EOP.

The spoof settings are inter-related, but the Show first contact safety tip setting has no dependency on spoof settings.

Quarantine policies define what users are able to do to quarantined messages, and whether users receive quarantine notifications. For more information, see Anatomy of a quarantine policy.

Although the Apply quarantine policy value appears unselected when you create an anti-phishing policy in the Defender portal, the quarantine policy named DefaultFullAccessPolicy¹ is used if you don't select a quarantine policy. This policy enforces the historical capabilities for messages that were quarantined as spoof as described in the table here. When you later view or edit the quarantine policy settings, the quarantine policy name is shown.

Admins can create or use quarantine policies with more restrictive or less restrictive capabilities. For instructions, see Create quarantine policies in the Microsoft 365 Defender portal.

Security feature name	Default	Standard	Strict	Comment
Phishing threshold & protection
Enable spoof intelligence EnableSpoofIntelligence	Selected $true	Selected $true	Selected $true
Actions
Honor DMARC record policy when the message when the message is detected as spoof HonorDmarcPolicy	Not selected $false	Not selected $false	Not selected $false	This setting is currently in Preview. When this setting is turned on, you control what happens to messages where the sender fails explicit DMARC checks when the policy action in the DMARC TXT record is set to p=quarantine or p=reject. For more information, see Spoof protection and sender DMARC policies.
If the message is detected as spoof and DMARC Policy is set as p=quarantine DmarcQuarantineAction	Quarantine the message Quarantine	Quarantine the message Quarantine	Quarantine the message Quarantine	This setting is currently in Preview. This action is meaningful only when Honor DMARC record policy when the message when the message is detected as spoof is turned on.
If the message is detected as spoof and DMARC Policy is set as p=reject DmarcRejectAction	Quarantine the message Quarantine	Quarantine the message Quarantine	Quarantine the message Quarantine	This setting is currently in Preview. This action is meaningful only when Honor DMARC record policy when the message when the message is detected as spoof is turned on.
If the message is detected as spoof and DMARC Policy is set as p=reject DmarcRejectAction	Quarantine the message Quarantine	Quarantine the message Quarantine	Quarantine the message Quarantine	This setting is currently in Preview. This action is meaningful only when Honor DMARC record policy when the message when the message is detected as spoof is turned on.
If the message is detected as spoof by spoof intelligence AuthenticationFailAction	Move the message to the recipients' Junk Email folders MoveToJmf	Move the message to the recipients' Junk Email folders MoveToJmf	Quarantine the message Quarantine	This setting applies to spoofed senders that were automatically blocked as shown in the spoof intelligence insight or manually blocked in the Tenant Allow/Block List. If you select Quarantine the message as the action for the spoof verdict, an Apply quarantine policy box is available.
Quarantine policy for Spoof SpoofQuarantineTag	DefaultFullAccessPolicy¹	DefaultFullAccessPolicy	DefaultFullAccessWithNotificationPolicy	The quarantine policy is meaningful only if spoof detections are quarantined.
Show first contact safety tip EnableFirstContactSafetyTips	Not selected $false	Not selected $false	Not selected $false	For more information, see First contact safety tip.
Show (?) for unauthenticated senders for spoof EnableUnauthenticatedSender	Selected $true	Selected $true	Selected $true	Adds a question mark (?) to the sender's photo in Outlook for unidentified spoofed senders. For more information, see Unauthenticated sender indicators.
Show "via" tag EnableViaTag	Selected $true	Selected $true	Selected $true	Adds a via tag (chris@contoso.com via fabrikam.com) to the From address if it's different from the domain in the DKIM signature or the MAIL FROM address. For more information, see Unauthenticated sender indicators.

¹ As described in Full access permissions and quarantine notifications, your organization might use NotificationEnabledPolicy instead of DefaultFullAccessPolicy in the default security policy or in new custom security policies that you create. The only difference between these two quarantine policies is quarantine notifications are turned on in NotificationEnabledPolicy and turned off in DefaultFullAccessPolicy.

Microsoft Defender for Office 365 security

Additional security benefits come with a Microsoft Defender for Office 365 subscription. For the latest news and information, you can see What's new in Defender for Office 365.

Important

• The default anti-phishing policy in Microsoft Defender for Office 365 provides spoof protection and mailbox intelligence for all recipients. However, the other available impersonation protection features and advanced settings are not configured or enabled in the default policy. To enable all protection features, use one of the following methods:

  • Turn on and use the Standard and/or Strict preset security policies and configure impersonation protection there.

  • Modify the default anti-phishing policy.

  • Create additional anti-phishing policies.

• Although there's no default Safe Attachments policy or Safe Links policy, the Built-in protection preset security policy provides Safe Attachments protection and Safe Links protection to all recipients (users who aren't defined in the Standard or Strict preset security policies or in custom Safe Attachments policies or Safe Links policies). For more information, see Preset security policies in EOP and Microsoft Defender for Office 365.

• Safe Attachments for SharePoint, OneDrive, and Microsoft Teams protection and Safe Documents protection have no dependencies on Safe Links policies.

If your subscription includes Microsoft Defender for Office 365 or if you've purchased Defender for Office 365 as an add-on, set the following Standard or Strict configurations.

Anti-phishing policy settings in Microsoft Defender for Office 365

EOP customers get basic anti-phishing as previously described, but Defender for Office 365 includes more features and control to help prevent, detect, and remediate against attacks. To create and configure these policies, see Configure anti-phishing policies in Defender for Office 365.

Advanced settings in anti-phishing policies in Microsoft Defender for Office 365

For more information about this setting, see Advanced phishing thresholds in anti-phishing policies in Microsoft Defender for Office 365. To configure this setting, see Configure anti-phishing policies in Defender for Office 365.

Security feature name	Default	Standard	Strict	Comment
Phishing email threshold PhishThresholdLevel	1 - Standard 1	3 - More aggressive 3	4 - Most aggressive 4

Impersonation settings in anti-phishing policies in Microsoft Defender for Office 365

For more information about these settings, see Impersonation settings in anti-phishing policies in Microsoft Defender for Office 365. To configure these settings, see Configure anti-phishing policies in Defender for Office 365.

Wherever you select Quarantine the message as the action for an impersonation verdict, an Apply quarantine policy box is available. Quarantine policies define what users are able to do to quarantined messages, and whether users receive quarantine notifications. For more information, see Anatomy of a quarantine policy.

Although the Apply quarantine policy value appears unselected when you create an anti-phishing policy in the Defender portal, the quarantine policy named DefaultFullAccessPolicy is used if you don't select a quarantine policy. This policy enforces the historical capabilities for messages that were quarantined as impersonation as described in the table here. When you later view or edit the quarantine policy settings, the quarantine policy name is shown.

Admins can create or use quarantine policies with more restrictive or less restrictive capabilities. For instructions, see Create quarantine policies in the Microsoft 365 Defender portal.

Security feature name	Default	Standard	Strict	Comment
Phishing threshold & protection
Enable users to protect (impersonated user protection) EnableTargetedUserProtection TargetedUsersToProtect	Not selected $false none	Selected $true <list of users>	Selected $true <list of users>	We recommend adding users (message senders) in key roles. Internally, protected senders might be your CEO, CFO, and other senior leaders. Externally, protected senders could include council members or your board of directors.
Enable domains to protect (impersonated domain protection)	Not selected	Selected	Selected
Include domains I own EnableOrganizationDomainsProtection	Off $false	Selected $true	Selected $true
Include custom domains EnableTargetedDomainsProtection TargetedDomainsToProtect	Off $false none	Selected $true <list of domains>	Selected $true <list of domains>	We recommend adding domains (sender domains) that you don't own, but you frequently interact with.
Add trusted senders and domains ExcludedSenders ExcludedDomains	None	None	None	Depending on your organization, we recommend adding senders or domains that are incorrectly identified as impersonation attempts.
Enable mailbox intelligence EnableMailboxIntelligence	Selected $true	Selected $true	Selected $true
Enable intelligence for impersonation protection EnableMailboxIntelligenceProtection	Off $false	Selected $true	Selected $true	This setting allows the specified action for impersonation detections by mailbox intelligence.
Actions
If a message is detected as user impersonation TargetedUserProtectionAction	Don't apply any action NoAction	Quarantine the message Quarantine	Quarantine the message Quarantine
Quarantine policy for user impersonation TargetedUserQuarantineTag	DefaultFullAccessPolicy¹	DefaultFullAccessWithNotificationPolicy	DefaultFullAccessWithNotificationPolicy	The quarantine policy is meaningful only if user impersonation detections are quarantined.
If a message is detected as domain impersonation TargetedDomainProtectionAction	Don't apply any action NoAction	Quarantine the message Quarantine	Quarantine the message Quarantine
Quarantine policy for domain impersonation TargetedDomainQuarantineTag	DefaultFullAccessPolicy¹	DefaultFullAccessWithNotificationPolicy	DefaultFullAccessWithNotificationPolicy	The quarantine policy is meaningful only if domain impersonation detections are quarantined.
If mailbox intelligence detects an impersonated user MailboxIntelligenceProtectionAction	Don't apply any action NoAction	Move the message to the recipients' Junk Email folders MoveToJmf	Quarantine the message Quarantine
Quarantine policy for mailbox intelligence impersonation MailboxIntelligenceQuarantineTag	DefaultFullAccessPolicy¹	DefaultFullAccessPolicy	DefaultFullAccessWithNotificationPolicy	The quarantine policy is meaningful only if mailbox intelligence detections are quarantined.
Show user impersonation safety tip EnableSimilarUsersSafetyTips	Off $false	Selected $true	Selected $true
Show domain impersonation safety tip EnableSimilarDomainsSafetyTips	Off $false	Selected $true	Selected $true
Show user impersonation unusual characters safety tip EnableUnusualCharactersSafetyTips	Off $false	Selected $true	Selected $true

¹ As described in Full access permissions and quarantine notifications, your organization might use NotificationEnabledPolicy instead of DefaultFullAccessPolicy in the default security policy or in new custom security policies that you create. The only difference between these two quarantine policies is quarantine notifications are turned on in NotificationEnabledPolicy and turned off in DefaultFullAccessPolicy.

EOP anti-phishing policy settings in Microsoft Defender for Office 365

These are the same settings that are available in anti-spam policy settings in EOP.

Safe Attachments settings

Safe Attachments in Microsoft Defender for Office 365 includes global settings that have no relationship to Safe Attachments policies, and settings that are specific to each Safe Links policy. For more information, see Safe Attachments in Defender for Office 365.

Although there's no default Safe Attachments policy, the Built-in protection preset security policy provides Safe Attachments protection to all recipients (users who aren't defined in the Standard or Strict preset security policies or in custom Safe Attachments policies). For more information, see Preset security policies in EOP and Microsoft Defender for Office 365.

Global settings for Safe Attachments

Note

The global settings for Safe Attachments are set by the Built-in protection preset security policy, but not by the Standard or Strict preset security policies. Either way, admins can modify these global Safe Attachments settings at any time.

The Default column shows the values before the existence of the Built-in protection preset security policy. The Built-in protection column shows the values that are set by the Built-in protection preset security policy, which are also our recommended values.

To configure these settings, see Turn on Safe Attachments for SharePoint, OneDrive, and Microsoft Teams and Safe Documents in Microsoft 365 E5.

In PowerShell, you use the Set-AtpPolicyForO365 cmdlet for these settings.

Security feature name	Default	Built-in protection	Comment
Turn on Defender for Office 365 for SharePoint, OneDrive, and Microsoft Teams EnableATPForSPOTeamsODB	Off $false	On $true	To prevent users from downloading malicious files, see Use SharePoint Online PowerShell to prevent users from downloading malicious files.
Turn on Safe Documents for Office clients EnableSafeDocs	Off $false	On $true	This feature is available and meaningful only with licenses that are not included in Defender for Office 365 (for example, Microsoft 365 A5 or Microsoft 365 E5 Security). For more information, see Safe Documents in Microsoft 365 A5 or E5 Security.
Allow people to click through Protected View even if Safe Documents identified the file as malicious AllowSafeDocsOpen	Off $false	Off $false	This setting is related to Safe Documents.

Safe Attachments policy settings

To configure these settings, see Set up Safe Attachments policies in Defender for Office 365.

In PowerShell, you use the New-SafeAttachmentPolicy and Set-SafeAttachmentPolicy cmdlets for these settings.

Note

As described earlier, there is no default Safe Attachments policy, but Safe Attachments protection is assigned to all recipients by the Built-in protection preset security policy (users who aren't defined in any Safe Attachments policies).

The Default in custom column refers to the default values in new Safe Attachments policies that you create. The remaining columns indicate (unless otherwise noted) the values that are configured in the corresponding preset security policies.

Quarantine policies define what users are able to do to quarantined messages, and whether users receive quarantine notifications. For more information, see Anatomy of a quarantine policy.

The policy named AdminOnlyAccessPolicy enforces the historical capabilities for messages that were quarantined as malware as described in the table here.

Users can't release their own messages that were quarantined as malware by Safe Attachments, regardless of how the quarantine policy is configured. If the policy allows users to release their own quarantined messages, users are instead allowed to request the release of their quarantined malware messages.

Security feature name	Default in custom	Built-in protection	Standard	Strict	Comment
Safe Attachments unknown malware response Enable and Action	Off -Enable $false and -Action Block	Block -Enable $true and -Action Block	Block -Enable $true and -Action Block	Block -Enable $true and -Action Block	When the Enable parameter is $false, the value of the Action parameter doesn't matter.
Quarantine policy QuarantineTag	AdminOnlyAccessPolicy	AdminOnlyAccessPolicy	AdminOnlyAccessPolicy	AdminOnlyAccessPolicy
Redirect attachment with detected attachments : Enable redirect Redirect RedirectAddress	Not selected and no email address specified. -Redirect $false RedirectAddress is blank ($null)	Not selected and no email address specified. -Redirect $false RedirectAddress is blank ($null)	Selected and specify an email address. $true an email address	Selected and specify an email address. $true an email address	Redirect messages to a security admin for review. Note: This setting is not configured in the Standard, Strict, or Built-in protection preset security policies. The Standard and Strict values indicate our recommended values in new Safe Attachments policies that you create.
Apply the Safe Attachments detection response if scanning can't complete (timeout or errors) ActionOnError	Selected $true	Selected $true	Selected $true	Selected $true

Safe Links policy settings

For more information about Safe Links protection, see Safe Links in Defender for Office 365.

Although there's no default Safe Links policy, the Built-in protection preset security policy provides Safe Links protection to all recipients (users who aren't defined in the Standard or Strict preset security policies or in custom Safe Links policies). For more information, see Preset security policies in EOP and Microsoft Defender for Office 365.

To configure Sae Links policy settings, see Set up Safe Links policies in Microsoft Defender for Office 365.

In PowerShell, you use the New-SafeLinksPolicy and Set-SafeLinksPolicy cmdlets for Safe Links policy settings.

Note

The Default in custom column refers to the default values in new Safe Links policies that you create. The remaining columns indicate (unless otherwise noted) the values that are configured in the corresponding preset security policies.

Security feature name	Default in custom	Built-in protection	Standard	Strict	Comment
URL & click protection settings
Email					The settings in this section affect URL rewriting and time of click protection in email messages.
On: Safe Links checks a list of known, malicious links when users click links in email. URLs are rewritten by default. EnableSafeLinksForEmail	Selected $true	Selected $true	Selected $true	Selected $true
Apply Safe Links to email messages sent within the organization EnableForInternalSenders	Selected $true	Not selected $false	Selected $true	Selected $true
Apply real-time URL scanning for suspicious links and links that point to files ScanUrls	Selected $true	Selected $true	Selected $true	Selected $true
Wait for URL scanning to complete before delivering the message DeliverMessageAfterScan	Selected $true	Selected $true	Selected $true	Selected $true
Do not rewrite URLs, do checks via Safe Links API only DisableURLRewrite	Selected* $true	Selected $true	Not selected $false	Not selected $false	* In new Safe Links policies that you create in the Defender portal, this setting is selected by default. In new Safe Links policies that you create in PowerShell, the default value of the DisableURLRewrite parameter is $false.
Do not rewrite the following URLs in email DoNotRewriteUrls	Blank $null	Blank $null	Blank $null	Blank $null	We have no specific recommendation for this setting. Note: Entries in the "Do not rewrite the following URLs" list are not scanned or wrapped by Safe Links during mail flow. Use allow URL entries in the Tenant Allow/Block List so URLs are not scanned or wrapped by Safe Links during mail flow and at time of click.
Teams					The setting in this section affects time of click protection in Microsoft Teams.
On: Safe Links checks a list of known, malicious links when users click links in Microsoft Teams. URLs are not rewritten. EnableSafeLinksForTeams	Selected $true	Selected $true	Selected $true	Selected $true
Office 365 apps					The setting in this section affects time of click protection in Office apps.
On: Safe Links checks a list of known, malicious links when users click links in Microsoft Office apps. URLs are not rewritten. EnableSafeLinksForOffice	Selected $true	Selected $true	Selected $true	Selected $true	Use Safe Links in supported Office 365 desktop and mobile (iOS and Android) apps. For more information, see Safe Links settings for Office apps.
Click protection settings
Track user clicks TrackClicks	Selected $true	Selected $true	Selected $true	Selected $true
Let users click through to the original URL AllowClickThrough	Selected* $true	Selected $true	Not selected $false	Not selected $false	* In new Safe Links policies that you create in the Defender portal, this setting is selected by default. In new Safe Links policies that you create in PowerShell, the default value of the AllowClickThrough parameter is $false.
Display the organization branding on notification and warning pages EnableOrganizationBranding	Not selected $false	Not selected $false	Not selected $false	Not selected $false	We have no specific recommendation for this setting. Before you turn on this setting, you need to follow the instructions in Customize the Microsoft 365 theme for your organization to upload your company logo.
Notification
How would you like to notify your users? CustomNotificationText UseTranslatedNotificationText	Use the default notification text Blank ($null) $false	Use the default notification text Blank ($null) $false	Use the default notification text Blank ($null) $false	Use the default notification text Blank ($null) $false	We have no specific recommendation for this setting. You can select Use custom notification text (-CustomNotificationText "<Custom text>") to enter and use customized notification text. If you specify custom text, you can also select Use Microsoft Translator for automatic localization (-UseTranslatedNotificationText $true) to automatically translate the text into the user's language.

Related articles

• Are you looking for best practices for Exchange mail flow rules (also known as transport rules)? See Best practices for configuring mail flow rules in Exchange Online.

• Admins and users can submit false positives (good email marked as bad) and false negatives (bad email allowed) to Microsoft for analysis. For more information, see Report messages and files to Microsoft.

• Use these links for info on how to set up your EOP service, and configure Microsoft Defender for Office 365. Don't forget the helpful directions in 'Protect Against Threats in Office 365'.

• Security baselines for Windows can be found here: Where can I get the security baselines? for GPO/on-premises options, and Use security baselines to configure Windows devices in Intune for Intune-based security. Finally, a comparison between Microsoft Defender for Endpoint and Microsoft Intune security baselines is available in Compare the Microsoft Defender for Endpoint and the Windows Intune security baselines.