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Allow or block URLs using the Tenant Allow/Block List

Tip

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

In Microsoft 365 organizations with mailboxes in Exchange Online or standalone Exchange Online Protection (EOP) organizations without Exchange Online mailboxes, admins can create and manage entries for URLs in the Tenant Allow/Block List. For more information about the Tenant Allow/Block List, see Manage allows and blocks in the Tenant Allow/Block List.

Note

To allow phishing URLs from third-party phishing simulations, use the advanced delivery configuration to specify the URLs. Don't use the Tenant Allow/Block List.

This article describes how admins can manage entries for URLs in the Microsoft Defender portal and in Exchange Online PowerShell.

What do you need to know before you begin?

  • You open the Microsoft Defender portal at https://security.microsoft.com. To go directly to the Tenant Allow/Block List page, use https://security.microsoft.com/tenantAllowBlockList. To go directly to the Submissions page, use https://security.microsoft.com/reportsubmission.

  • To connect to Exchange Online PowerShell, see Connect to Exchange Online PowerShell. To connect to standalone EOP PowerShell, see Connect to Exchange Online Protection PowerShell.

  • For URL entry syntax, see the URL syntax for the Tenant Allow/Block List section later in this article.

    • Entry limits for URLs:
    • Exchange Online Protection: The maximum number of allow entries is 500, and the maximum number of block entries is 500 (1000 URL entries in total).
    • Defender for Office 365 Plan 1: The maximum number of allow entries is 1000, and the maximum number of block entries is 1000 (2000 URL entries in total).
    • Defender for Office 365 Plan 2: The maximum number of allow entries is 5000, and the maximum number of block entries is 10000 (15000 URL entries in total).

  • You can enter a maximum of 250 characters in a URL entry.

  • An entry should be active within 5 minutes.

  • You need to be assigned permissions before you can do the procedures in this article. You have the following options:

    • Microsoft Defender XDR Unified role based access control (RBAC) (If Email & collaboration > Defender for Office 365 permissions is Active. Affects the Defender portal only, not PowerShell):

      • Add and remove entries from the Tenant Allow/Block List: Membership assigned with the following permissions:
        • Authorization and settings/Security settings/Detection tuning (manage)
      • Read-only access to the Tenant Allow/Block List:
        • Authorization and settings/Security settings/Read-only.
        • Authorization and settings/Security settings/Core Security settings (read).

    • Exchange Online permissions:

      • Add and remove entries from the Tenant Allow/Block List: Membership in one of the following role groups:
        • Organization Management or Security Administrator (Security admin role).
        • Security Operator (Tenant AllowBlockList Manager).
      • Read-only access to the Tenant Allow/Block List: Membership in one of the following role groups:
        • Global Reader
        • Security Reader
        • View-Only Configuration
        • View-Only Organization Management

    • Microsoft Entra permissions: Membership in the Global Administrator*, Security Administrator, Global Reader, or Security Reader roles gives users the required permissions and permissions for other features in Microsoft 365.

      Important

      * Microsoft recommends that you use roles with the fewest permissions. Using lower permissioned accounts helps improve security for your organization. Global Administrator is a highly privileged role that should be limited to emergency scenarios when you can't use an existing role.

Create allow entries for URLs

You can't create allow entries for URLs directly in the Tenant Allow/Block List. Unnecessary allow entries expose your organization to malicious email that would have been filtered by the system.

Instead, you use the URLs tab on the Submissions page at https://security.microsoft.com/reportsubmission?viewid=url. When you submit a blocked URL as I've confirmed it's clean, you can select Allow this URL to add and allow entry for the URL on the URLs tab on the Tenant Allow/Block Lists page. For instructions, see Report good URLs to Microsoft.

Tip

Allow entries from submissions are added during mail flow based on the filters that determined the message was malicious. For example, if the sender email address and a URL in the message are determined to be malicious, an allow entry is created for the sender (email address or domain) and the URL.

During mail flow or time of click, if messages containing the entities in the allow entries pass other checks in the filtering stack, the messages are delivered (all filters associated with the allowed entities are skipped). For example, if a message passes email authentication checks, URL filtering, and file filtering, a message from an allowed sender email address is delivered if it's also from an allowed sender.

By default, allow entries for domains and email addresses, files, and URLs are kept for 45 days after the filtering system determines that the entity is clean, and then the allow entry is removed. Or you can set allow entries to expire up to 30 days after you create them. Allow entries for spoofed senders never expire.

During time of click, the URL allow entry overrides all filters associated with the URL entity, which allows users to access the URL.

A URL allow entry doesn't prevent the URL from being wrapped by Safe Links protection in Defender for Office 365. For more information, see Do not rewrite list in SafeLinks.

Create block entries for URLs

Email messages that contain these blocked URLs are blocked as high confidence phishing. Messages that contain the blocked URLs are quarantined.

To create block entries for URLs, use either of the following methods:

You have the following options to create block entries for URLs:

Use the Microsoft Defender portal to create block entries for URLs in the Tenant Allow/Block List

  1. In the Microsoft Defender portal at https://security.microsoft.com, go to Policies & rules > Threat Policies > Rules section > Tenant Allow/Block Lists. Or, to go directly to the Tenant Allow/Block List page, use https://security.microsoft.com/tenantAllowBlockList.

  2. On the Tenant Allow/Block List page, select the URLs tab.

  3. On the URLs tab, select Block.

  4. In the Block URLs flyout that opens, configure the following settings:

    • Add URLs with wildcards: Enter one URL per line, up to a maximum of 20. For details about the syntax for URL entries, see the URL syntax for the Tenant Allow/Block List section later in this article.

    • Remove block entry after: Select from the following values:

      • Never expire
      • 1 day
      • 7 days
      • 30 days (default)
      • Specific date: The maximum value is 90 days from today.

    • Optional note: Enter descriptive text for why you're blocking the URLs.

    When you're finished in the Block URLs flyout, select Add.

Back on the URLs tab, the entry is listed.

Use PowerShell to create block entries for URLs in the Tenant Allow/Block List

In Exchange Online PowerShell, use the following syntax:

New-TenantAllowBlockListItems -ListType Url -Block -Entries "Value1","Value2",..."ValueN" <-ExpirationDate <Date> | -NoExpiration> [-Notes <String>]

This example adds a block entry for the URL contoso.com and all subdomains (for example, contoso.com and xyz.abc.contoso.com). Because we didn't use the ExpirationDate or NoExpiration parameters, the entry expires after 30 days.

New-TenantAllowBlockListItems -ListType Url -Block -Entries *contoso.com

For detailed syntax and parameter information, see New-TenantAllowBlockListItems.

Use the Microsoft Defender portal to view entries for URLs in the Tenant Allow/Block List

In the Microsoft Defender portal at https://security.microsoft.com, go to Policies & rules > Threat Policies > Tenant Allow/Block Lists in the Rules section. Or, to go directly to the Tenant Allow/Block Lists page, use https://security.microsoft.com/tenantAllowBlockList.

Select the URLs tab.

On the URLs tab, you can sort the entries by clicking on an available column header. The following columns are available:

  • Value: The URL.
  • Action: The available values are Allow or Block.
  • Modified by
  • Last updated
  • Last used date: The date the entry was last used in the filtering system to override the verdict.
  • Remove on: The expiration date.
  • Notes

To filter the entries, select Filter. The following filters are available in the Filter flyout that opens:

  • Action: The available values are Allow and Block.
  • Never expire: or
  • Last updated: Select From and To dates.
  • Last used date: Select From and To dates.
  • Remove on: Select From and To dates.

When you're finished in the Filter flyout, select Apply. To clear the filters, select Clear filters.

Use the Search box and a corresponding value to find specific entries.

To group the entries, select Group and then select Action. To ungroup the entries, select None.

Use PowerShell to view entries for URLs in the Tenant Allow/Block List

In Exchange Online PowerShell, use the following syntax:

Get-TenantAllowBlockListItems -ListType Url [-Allow] [-Block] [-Entry <URLValue>] [<-ExpirationDate <Date> | -NoExpiration>]

This example returns all allowed and blocked URLs.

Get-TenantAllowBlockListItems -ListType Url

This example filters the results by blocked URLs.

Get-TenantAllowBlockListItems -ListType Url -Block

For detailed syntax and parameter information, see Get-TenantAllowBlockListItems.

Use the Microsoft Defender portal to modify entries for URLs in the Tenant Allow/Block List

In existing URL entries, you can change the expiration date and note.

  1. In the Microsoft Defender portal at https://security.microsoft.com, go to Policies & rules > Threat Policies > Rules section > Tenant Allow/Block Lists. Or, to go directly to the Tenant Allow/Block Lists page, use https://security.microsoft.com/tenantAllowBlockList.

  2. Select the URLs tab

  3. On the URLs tab, select the entry from the list by selecting the check box next to the first column, and then select the Edit action that appears.

  4. In the Edit URL flyout that opens, the following settings are available:

    • Block entries:
      • Remove block entry after: Select from the following values:
        • 1 day
        • 7 days
        • 30 days
        • Never expire
        • Specific date: The maximum value is 90 days from today.
      • Optional note
    • Allow entries:
      • Remove allow entry after: Select from the following values:
        • 1 day
        • 7 days
        • 30 days
        • 45 days after last used date
        • Specific date: The maximum value is 30 days from today.
      • Optional note

    When you're finished in the Edit URL flyout, select Save.

Tip

In the details flyout of an entry on the URLs tab, use View submission at the top of the flyout to go to the details of the corresponding entry on the Submissions page. This action is available if a submission was responsible for creating the entry in the Tenant Allow/Block List.

Use PowerShell to modify entries for URLs in the Tenant Allow/Block List

In Exchange Online PowerShell, use the following syntax:

Set-TenantAllowBlockListItems -ListType Url <-Ids <Identity value> | -Entries <Value>> [<-ExpirationDate Date | -NoExpiration>] [-Notes <String>]

This example changes the expiration date of the block entry for the specified URL.

Set-TenantAllowBlockListItems -ListType Url -Entries "~contoso.com" -ExpirationDate "9/1/2022"

For detailed syntax and parameter information, see Set-TenantAllowBlockListItems.

Use the Microsoft Defender portal to remove entries for URLs from the Tenant Allow/Block List

  1. In the Microsoft Defender portal at https://security.microsoft.com, go to Policies & rules > Threat Policies > Rules section > Tenant Allow/Block Lists. Or, to go directly to the Tenant Allow/Block List page, use https://security.microsoft.com/tenantAllowBlockList.

  2. Select the URLs tab.

  3. On the URLs tab, do one of the following steps:

    • Select the entry from the list by selecting the check box next to the first column, and then select the Delete action that appears.

    • Select the entry from the list by clicking anywhere in the row other than the check box. In the details flyout that opens, select Delete at the top of the flyout.

      Tip

      To see details about other entries without leaving the details flyout, use Previous item and Next item at the top of the flyout.

  4. In the warning dialog that opens, select Delete.

Back on the URLs tab, the entry is no longer listed.

Tip

You can select multiple entries by selecting each check box, or select all entries by selecting the check box next to the Value column header.

Use PowerShell to remove entries for URLs from the Tenant Allow/Block List

In Exchange Online PowerShell, use the following syntax:

Remove-TenantAllowBlockListItems -ListType Url <-Ids <Identity value> | -Entries <Value>>

This example removes the block entry for the specified URL from the Tenant Allow/Block List.

Remove-TenantAllowBlockListItems -ListType Url -Entries "*cohovineyard.com

For detailed syntax and parameter information, see Remove-TenantAllowBlockListItems.

URL syntax for the Tenant Allow/Block List

  • IPv4 and IPv6 addresses are allowed, but TCP/UDP ports aren't.

  • Filename extensions aren't allowed (for example, test.pdf).

  • Unicode isn't supported, but Punycode is.

  • Hostnames are allowed if all of the following statements are true:

    • The hostname contains a period.
    • There is at least one character to the left of the period.
    • There are at least two characters to the right of the period.

    For example, t.co is allowed; .com or contoso. aren't allowed.

  • Subpaths aren't implied for allows.

    For example, contoso.com doesn't include contoso.com/a.

  • Wildcards (*) are allowed in the following scenarios:

    • A left wildcard must be followed by a period to specify a subdomain. (applicable only for blocks)

      For example, *.contoso.com is allowed; *contoso.com isn't allowed.

    • A right wildcard must follow a forward slash (/) to specify a path.

      For example, contoso.com/* is allowed; contoso.com* or contoso.com/ab* aren't allowed.

    • *.com* is invalid (not a resolvable domain and the right wildcard doesn't follow a forward slash).

    • Wildcards aren't allowed in IP addresses.

  • The tilde (~) character is available in the following scenarios:

    • A left tilde implies a domain and all subdomains.

      For example, ~contoso.com includes contoso.com and *.contoso.com.

  • A username or password isn't supported or required.

  • Quotes (' or ") are invalid characters.

  • A URL should include all redirects where possible.

URL entry scenarios

Valid URL entries and their results are described in the following subsections.

Scenario: Top-level domain blocking

Entry: *.<TLD>/*

  • Block match:
    • a.TLD
    • TLD/abcd
    • b.abcd.TLD
    • TLD/contoso.com
    • TLD/q=contoso.com
    • www.abcd.com\xyz.TLD
    • www.abcd.com\xyz.TLD?q=1234
    • www.abcd.TLD
    • www.abcd.TLD/q=a@contoso.com

Scenario: No wildcards

Entry: contoso.com

  • Allow match: contoso.com

  • Allow not matched:

    • abc-contoso.com
    • contoso.com/a
    • abc.xyz.contoso.com/a/b/c
    • payroll.contoso.com
    • test.com/contoso.com
    • test.com/q=contoso.com
    • www.contoso.com
    • www.contoso.com/q=a@contoso.com

  • Block match:

    • contoso.com
    • contoso.com/a
    • abc.xyz.contoso.com/a/b/c
    • payroll.contoso.com
    • test.com/contoso.com
    • test.com/q=contoso.com
    • www.contoso.com
    • www.contoso.com/q=a@contoso.com

  • Block not matched: abc-contoso.com

Scenario: Left wildcard (subdomain)

Tip

Allow entries of this pattern are supported only from advanced delivery configuration.

Entry: *.contoso.com

  • Allow match and Block match:

    • www.contoso.com
    • xyz.abc.contoso.com

  • Allow not matched and Block not matched:

    • 123contoso.com
    • contoso.com
    • test.com/contoso.com
    • www.contoso.com/abc

Scenario: Right wildcard at top of path

Entry: contoso.com/a/*

  • Allow match and Block match:

    • contoso.com/a/b
    • contoso.com/a/b/c
    • contoso.com/a/?q=joe@t.com

  • Allow not matched and Block not matched:

    • contoso.com
    • contoso.com/a
    • www.contoso.com
    • www.contoso.com/q=a@contoso.com

Scenario: Left tilde

Tip

Allow entries of this pattern are supported only from advanced delivery configuration.

Entry: ~contoso.com

  • Allow match and Block match:

    • contoso.com
    • www.contoso.com
    • xyz.abc.contoso.com

  • Allow not matched and Block not matched:

    • 123contoso.com
    • contoso.com/abc
    • www.contoso.com/abc

Scenario: Right wildcard suffix

Entry: contoso.com/*

  • Allow match and Block match:

    • contoso.com/?q=whatever@fabrikam.com
    • contoso.com/a
    • contoso.com/a/b/c
    • contoso.com/ab
    • contoso.com/b
    • contoso.com/b/a/c
    • contoso.com/ba

  • Allow not matched and Block not matched: contoso.com

Scenario: Left wildcard subdomain and right wildcard suffix

Tip

Allow entries of this pattern are supported only from advanced delivery configuration.

Entry: *.contoso.com/*

  • Allow match and Block match:

    • abc.contoso.com/ab
    • abc.xyz.contoso.com/a/b/c
    • www.contoso.com/a
    • www.contoso.com/b/a/c
    • xyz.contoso.com/ba

  • Allow not matched and Block not matched: contoso.com/b

Scenario: Left and right tilde

Tip

Allow entries of this pattern are supported only from advanced delivery configuration.

Entry: ~contoso.com~

  • Allow match and Block match:

    • contoso.com
    • contoso.com/a
    • www.contoso.com
    • www.contoso.com/b
    • xyz.abc.contoso.com
    • abc.xyz.contoso.com/a/b/c
    • contoso.com/b/a/c
    • test.com/contoso.com

  • Allow not matched and Block not matched:

    • 123contoso.com
    • contoso.org
    • test.com/q=contoso.com

Scenario: IP address

Entry: 1.2.3.4

  • Allow match and Block match: 1.2.3.4

  • Allow not matched and Block not matched:

    • 1.2.3.4/a
    • 11.2.3.4/a

IP address with right wildcard

Entry: 1.2.3.4/*

  • Allow match and Block match:
    • 1.2.3.4/b
    • 1.2.3.4/baaaa

Examples of invalid entries

The following entries are invalid:

  • Missing or invalid domain values:

    • contoso
    • *.contoso.*
    • *.com
    • *.pdf

  • Wildcard on text or without spacing characters:

    • *contoso.com
    • contoso.com*
    • *1.2.3.4
    • 1.2.3.4*
    • contoso.com/a*
    • contoso.com/ab*

  • IP addresses with ports:

    • contoso.com:443
    • abc.contoso.com:25

  • Non-descriptive wildcards:

    • *
    • *.*

  • Middle wildcards:

    • conto*so.com
    • conto~so.com

  • Double wildcards

    • contoso.com/**
    • contoso.com/*/*