When “block” doesn’t mean necessarily “block”

I just came across this and I was really puzzled as I never thought something like this would happen:

What do you expect, if you use a feature, which states that you could block specific senders?

Right, you feed the system and messages from these senders will never made it to protected recipient.

Well, let me tell you that the feature Tenant Allow/Block List (TABL) of Microsoft Defender for Office 365 (MDO)is exactly doing this:

Promising that you can block senders, but actually deliver messages to mailboxes depending on your anti-spam policy settings.

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When OOF makes you hit EXO limits and you’re blocked from receiving emails

I recently came across something you might also run into at this time of the year or when a company wide announcement needs to be made via e-mail and the sender is in Exchange Online:

A person sent some season’s greetings, which results into being blocked by EXO as a limit was reached (you can find more about these limits here). My first thought was something like sending e.g.: 10.000 messages per day or too many recipients, but it turned out to be something different.

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When AAD, EXO and MS Teams creating a mess

I’m dealing with these issues already for a long time. But meanwhile, after a couple of support cases, the fog seems to lifting.

When you don’t have the following setup, you can stop reading:

  • create accounts for partners in your on-premises Active Directory (AD)
  • sync these accounts to Azure Active Directory (AAD)
  • Exchange RecipientType is MailUser
  • you assign one of the following licenses:
    • Customer Lockbox (in combination with SPO)
    • Microsoft 365 Advanced Auditing

For the others, feel free continue reading. It might open your eyes for some issues your facing.

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ApplicationAccessPolicy for EWS

I’m really excited about the fact that Microsoft fulfilled the ask for supporting Exchange Web Services (EWS) protocol in ApplicationAccessPolicy as announced here:

https://techcommunity.microsoft.com/t5/exchange-team-blog/application-access-policy-support-in-ews/ba-p/2110361

Unfortunately Microsoft seems to make it harder for you to add EWS permission full_access_as_app to your app.

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Microsoft Graph: Get group info

As mentioned in my previous post here, daily tasks shifted and so I had a closer look into Microsoft Graph. In this post it’s about retrieving group information.

Background

In my daily work, I often have to deal with topics, where I need to collect more information about a group. Yes, the new UI in the AAD portal helps, but doesn’t provide all the information. On the other side there are a ton of PowerShell modules e.g.: MSOL, AzureAD or AzureADPreview.

Sorry, but I’m unhappy as not one module, gives me all information. In fact in some cases I have to use MSOL and AzureADPreview in order to get the whole picture. Besides the fact that some Cmdlets just throw an error in larger environements.

Solution

The only solution for me was to use Microsoft Graph and therefore, I wrote a function called Get-MSGraphGroup. Same like my other function Get-MSGraphUser, it incorporates all techniques from Microsoft Graph:

The function has the following parameters:

.SYNOPSIS
    This function uses Microsoft Office application for retrieving access token and queries Microsoft Graph for group properties.
.DESCRIPTION
    The Microsoft Office with ClientID d3590ed6-52b3-4102-aeff-aad2292ab01c can be used to retrieve an access token with the scopes AuditLog.Read.All, Calendar.ReadWrite, Calendars.Read.Shared, Calendars.ReadWrite, Contacts.ReadWrite, DeviceManagementConfiguration.Read.All, DeviceManagementConfiguration.ReadWrite.All, Directory.AccessAsUser.All, Directory.Read.All, email, Files.Read, Files.Read.All, Group.Read.All, Group.ReadWrite.All, Mail.ReadWrite, openid, People.Read, People.Read.All, profile, User.Read.All, User.ReadWrite, Users.Read
.PARAMETER Group
    The parameter Group defines the id of the group. Unless you use the parameter ByMail. If this parameter is used in addition, the function tries to get the id of the group by searching for a group with the specified e-mail address.
.PARAMETER AccessToken
    This optional parameter AccessToken can be used if you want to use your own application with delegated or application permission. The parameter takes a previously acquired access token.
.PARAMETER ByMail
    The parameter ByMail is a switch, which can be used in combination with Group, when an e-mail address instead of an id is used.
.PARAMETER Filter
    The parameter Filter can be used, when you want to use a complex filter.
.PARAMETER ShowProgress
    The parameter ShowProgress will show the progress of the script.
.PARAMETER ReturnMembers
    Switch to return members of group.
.PARAMETER ReturnMembersTransitive
    Switch to return transitive members of group.
.PARAMETER Threads
    The parameter Threads defines how many Threads will be created. Only used in combination with MultiThread.
.PARAMETER MultiThread
    The parameters MultiThread defines whether the script is running using multithreading.
.PARAMETER Authority
    The authority from where you get the token.
.PARAMETER ClientId
    Application ID of the registered app.
.PARAMETER ClientSecret
    The secret, which is used for Client Credentials flow.
.PARAMETER Certificate
    The certificate, which is used for Client Credentials flow.
.PARAMETER MaxRetry
    How many retries for each user in case of error.
.PARAMETER TimeoutSec
    TimeoutSec for Cmdlet Invoke-RestMethod.
.PARAMETER MaxFilterResult
    MaxFilterResult when Filter is used.
.EXAMPLE
    Get-MSGraphGroup -Group ServicesSales@bla.com -ByMail
    Get-MSGraphGroup -Group 6288514a-9840-4426-as05-d2955a03ea27
    Get-MSGraphGroup -Filter Get-MSGraphGroup -Filter "startswith(mail,'ServicesSale')"
.NOTES
    If you want to use your own application make sure you have all the necessary minimum permission assigned: Group.Read.All (this might change in the future. Consult the full permission reference for Microsoft Graph)

It has basically same functionality like Get-MSGraphUser, with the difference that it retrieves data from groups.

Performance

The function also supports multi threading using PowerShell runspaces. On top of this it is important to understand the following parameters:

  • ReturnMembers
  • ReturnMembersTransitive

By default only the total number of members will be returned. IF you need to get all members, you can use one of those switches. Be aware that this can take a while and depends on how many members a group has.

You might wonder about the difference between both:

ReturnMembers will return only members of a group. This can also be another group. It will not recursively resolve all levels down to a user object.

ReturnMembersTransitive will exactly do this for you: recursively retrieve flat list of all users.

Example

Just to give you a real-life example. We receive very often tickets, where it is asked about checking Exchange for issues as it seems not all members of a group received an important e-mail.

Well, before it was some kind of hassle to get the flat list of users. Now with this it’s easy as you can just use Microsoft Graph and transitiveMembers.

Where can I get the code?

As mentioned in previous posts, I’m super lazy and that’s why I have it somehow automated to load all my little helpers in combination with a tweaked PowerShell profile. You can find my little helpers here:

https://github.com/IngoGege/Miscellaneous/blob/master/ExchangePowerShell/HelperFunctions.ps1

You might wonder about the needed application and permissions. No worries as you can use (partially) the app “Microsoft Office” (appId: d3590ed6-52b3-4102-aeff-aad2292ab01c), which is available to everyone and has even the scope Group.Read.All or Directory.Read.All. Usually these permissions require Global Admin consent!

Conclusion

I hope this code helps YOU in your daily work. Feedback is always welcome!

Update delegate collection challenge

A few days ago, I was approached by some Executive Support colleagues. The had to handle a lot of mail items in shared mailboxes. One issue the came across, was the fact that they had to move items and delete folders, but couldn’t as the folders contained private items.

Note: Don’t get me started about the use case “Private Items”! It doesn’t gives you any security value as it’s only honored by a few clients!

Well, back to the topic…I’m aware of this behavior and there is also a KB article about this topic:

“Cannot copy this folder because it may contain private items” error in Outlook

Since the shared mailbox is in M365 and the fasted way with least effort was to add the permissions for this user using Add-MailboxFolderPermission and make use of parameter -SharingPermissionFlags.

That’s what I thought and then run into this…

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Microsoft Graph: Get user info

Over the last weeks I had a steep learning curve with Microsoft Graph. In my daily job and especially as we moved to M365 it’s absolutely necessary querying attributes for users.

On-premises you most likely would use Get-AdUser or even just ADSI to do so. With the move to M365 you will call Microsoft Graph. And of course make use of OAuth2.0 flows for authentication and authorization.

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