Ionut Nica

I seem to be doing quite a bit Powershell scripting these days, and some of related to MS Exchange 2007. One issue we had recently was that loose permissions on Distribution Lists with hundreds of users + too much spare time for some users generated a lot of unwanted message traffic. I don’t want to discuss prevention measures like restricting who can send emails to big DLs or using Microsoft AD RMS to restrict what can be done with emails. Our goal here is to clean up the mess .

Essentially you can get some info about the message and mailboxes, and use it with Export-mailbox to remove the data. That is how I initially found this link, but what is not written there is that you need to have all the prerequisites for running export-mailbox, and also running it on hundreds of mailboxes may take a while. I decided to do it my way,by building on what I found on that blog.

This is “Mass Remove message(s) from mailboxes – My Way”.Depending on your situation you can apply these steps multiple times:

1. Identify the message that started it all
2. Track the message on the Exchange Servers and compile a list of unique recipients of the message.
3. Remove the message from the offended mailboxes (there may be special requirements to perform the task, see here)

Identify Message

Getting the information should be pretty easy, someone probably forwarded you the copy of the message(s) to be dealt with. You want to get this info as a minimum: subject,sender,date and time message(s) was/were sent. When you have enough info, open the Exchange Management Console > Tools > Message Tracking and from there identify which of the events represent the time the message originally arrived on the Transport Servers. For that event grab the “MessageID” Value. We will use this in the following steps to find all events relating to that specific messageID.

Track Message

Assuming the worst case scenario you have to do tracking across all Exchange Transport Servers, the speed of the process depends on how close to your Exchange Transport Role Servers you are running the tracking. I suggest you make sure this process runs in the same LAN as the Exchange, especially the export-mailbox part. Anyhow, to get all messages sent by “baduser@foo.com” across all transport servers in your Exchange run this:

$TrackingLogResults = get-transportserver | where {$_.Name -like "<optional filter>"} | foreach-object  {Get-MessageTrackingLog -EventId DELIVER -MessageID <MessageID from Step1> -ResultSize Unlimited -server $_}

• Get-TransportServer gives you all the transport servers in the organization
• Where clause filters the servers list, you can leave it out, it is helpful if your HUB transport servers are named in a specific way, and you know the message did not leave the organization, so you can exclude a search on the Edge Servers.
• Foreach-Object cycles through all servers and performs the search
• Get-MessageTrackingLog searches each transport server tracking log for DELIVER Events that correspond to messages with that specific MessageID. It returns unlimited results. The server that is being searched is piped from the Foreach cmdlet.
• If you run the last cmdlet without the EventID filter, you will get lots of other EventID’s like fail,send,receive,routing,expand. You just need deliver, DELIVER is important because it basically says “OK, this message passed all of my checks I am now sending it to the Mailbox Server so it can submit it to the mailbox store”, so you get a list of just the actually affected mailboxes.

This may take a while to run. Once it is finished we have to get the list of people that the message was sent to. The easy answer would be “why not just do $TrackingLogsResults | select-object Recipients and pipe it along to something else?”

Well you can do that, but in some cases Recipients means actually a bunch of other addresses, and each recipient may appear multiple times in the entire list.

e.g. – this could be a list returned by the “easy” command

{john@foo.com}

{John@foo.com,Jane@foo.com}

{Jill@foo.com,Josh@foo.com,Jake@foo.com}

Having duplicates is inefficient, everything will take longer in next steps. What I wanted was to have a list without duplicates, plus I get to show you some more “nice” scripting stuff

Compile Recipients List

I spent quite some time figuring this out, so someone out there better find it useful . The next step involved a “google shovel” to “dig up” how to break up those objects into one big list. Then the plan was to have a list that just had the unique email addresses – ideally. So here’s the “magic”:

$RecipientsExpanded = @()
$RecipientsExpanded = $TrackingLogResults | foreach-object {$RecipientsExpanded  = $RecipientsExpanded  + ($_.Recipients)}
$RecipientsGrouped = $RecipientsExpanded | group-object
$UniqueRecipients = $RecipientsGrouped | select-object Name | sort-object -property name

• We created a blank array object that will host all recipients addresses in “expanded form”.
• For each result from the TrackingLog we added the array ($_.Recipients) to the $RecipientsExpanded array. At the end of this we have a single array with all the addresses, each an individual element in the array.
• The Group-Object cmdlet is used to group all addresses by their name and in the end you have the list of unique email addresses.

Actually remove offending messages

Please see this link if you are planning to export the messages to PST. What is left to do is to take a page from the MSExchangeTeam blog and run get-mailbox| export-mailbox combo, only we are doing it on a reduced scale, only on the mailboxes that need it, that why I went through all the trouble of making that list!

$MailboxesList = $UniqueRecipients | foreach-object {
      $Filter = "PrimarySmtpAddress -eq '"+$_.Name+"'"
      get-mailbox -ignoredefaultscope -resultsize unlimited -Filter $Filter}

The code above handles this task for forests with child domains. I covered reasoning and use of -Ignoredefaultscope and -Filter in a previous post.

#get current admin UserPrincipalName
$Admin = [Security.Principal.WindowsIdentity]::GetCurrent().Name
#elevating the administrator's account to fulll access over all affected mailboxes
Add-MailboxPermission $MailboxesList -AccessRights FullAccess -User $Admin
export-Mailbox -Identity $MailboxesList –ContentKeywords <enter part of message body> -Recipients <add recipients list> –TargetMailbox admin_ –TargetFolder "RecoveredEmails" –DeleteContent

• The final step grants the admin user full access over the mailbox. The account being granted that right is $Admin, the account under which the script is running, it contains the UserPrincipalName of that account.
• You also need to have admin rights on the “TargetMailbox” and the “TargetFolder” should also exist beforehand.
• We export the offending message(s) using Export-Mailbox. Here it is important to be very careful and make the filtering as strict as possible, since here you cannot remove a message based on the MessageID, so you could end up removing many more messages. Refer to the documentation for export-mailbox, for all available switches for this purpose.

After you run the last command get ready for some really long waiting, as it goes through all the mailboxes. Once it is finished, remove your permissions from those mailboxes.

Remove-MailboxPermission $MailboxesList -AccessRights FullAccess -User $Admin

Phew this was a long post, but validating everything I explained here, took a while. The post is also packed with bits and pieces that can be your building block for other Exchange Shell scripts. I tried to show you how to take Exchange TrackingLog data and build a list of unique recipient addresses that you can use to filter out an unwanted message you tracked in the logs, and do that using export-mailbox commandlet. If you have any feedback/corrections/omissions please feel free to leave a comment.

Happy Scripting!