Removing Duplicate Items from a Mailbox

powershellLast version: 1.4, June 24th, 2014.

For those involved with Exchange migration projects or managing Exchange environments, at some point you probably have experienced the situation where people ended up with duplicate items in their mailbox. Duplicate items can be caused by many things, but most common are:

  • Synchronization tools or plug-in. Entries from the mailbox are treated as new entries and as a consequence are added to the mailbox when synchronizing information back to the mailbox, creating duplicates. In the past, I’ve seen this happening with Nokia PC Suite and Google Apps Sync for example;
  • Importing existing data. Accidental import from – for example – a PST file to a mailbox  can lead to duplicate entries.

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When looking for a solution, you’ll probably encounter MSKB299349, “How to remove duplicate imported items in Outlook”. This article describes a manual procedure to remove duplicates entries from your calendar, contacts, inbox or other folders. Not a very helpful and labor intensive.

When continuing your search, you’ll find lots (I mean lots!) of tools and Outlook add-ins, like Vaita’s DIR or MAPILab’s Duplicate Remover. Not all this software is free (some even require payment per duplicate removal of appointments, contacts or e-mail) and some might not even work (MAPI-based tools may not work against Exchange 2013).

When you finally have selected a tool, in most cases they require installation of a piece of software and someone to perform the removal process using the tool or Outlook with add-in. When you’re an Apple shop you’ll require different tools, unless you’re running a Windows desktop somewhere (I’ll just pretend I didn’t hear you saying ‘Why don’t you install the tool on the Exchange server’).

Wouldn’t it be nice if you’d have a PowerShell script you can conveniently run from any workstation (or server) with PowerShell installed, removing those duplicate items from a user’s mailbox remotely? If the answer is yes, the Remove-DuplicateItems.ps1 script may be something for you.

Requirements
Using the Remove-DuplicateItems.p1 script requires Exchange 2007 or later and Exchange Web Services (EWS) Managed API 1.2 (or later) which you can download here. Alternatively, when you already got the EWS Managed API Microsoft.Exchange.WebServices.DLL somewhere, you can copy it to the same folder where the script is located and it will be picked up. The script has been developed and tested against Exchange 2007, meaning it’s a PowerShell 1.0 script which should be compatible with later versions of PowerShell or Exchange.

Also take notice that since you’ll be processing user mailboxes, you’ll need to have full mailbox access or impersonation permissions; the latter is preferred. For details on how to configure impersonation for Exchange 2010 using RBAC, see this article or check here for details on how to configure impersonation for Exchange 2007.

Usage
The script Remove-DuplicateItems.ps1 uses the following syntax:

Remove-DuplicateItems.ps1 [-Mailbox] <String> [[-Type] <String>] [-Retain <String>] [-Server <String>] [-Impersonation] [-DeleteMode <String>] [-Credentials <PSCredential>] [-Mode <String>] [-MailboxOnly] [-ArchiveOnly] [-WhatIf] [-Confirm] [<CommonParameters>]

A quick walk-through on the parameters and switches:

  • Mailbox is the e-mail address or name of the mailbox to process. If name is used, it is matched against cn/SAMAccountname/email address of local AD.
  • Type determines what folders are checked for duplicates. Valid options are Mail, Calendar, Contacts, Tasks, Notes or All (Default).
  • Retain determines which item to retain by comparing last modification times. Valid options are Newest (default) or Oldest.
  • Server is the name of the Client Access Server to access for Exchange Web Services. When omitted, the script will attempt to use Autodiscover.
  • When the Impersonation switch is specified, impersonation will be used for mailbox access, otherwise the current user context will be used.
  • DeleteMode specifies how to remove messages. Possible values are HardDelete (permanently deleted), SoftDelete (use dumpster, default) or MoveToDeletedItems (move to Deleted Items folder).
  • Credentials specifies credentials to use (provide credentials using Get-Credential).
  • Mode determines how items are matched. Options are Quick, which uses PidTagSearchKey and is the default mode, or Full which uses a predefined set of attributes to match items, depending on the item class:
ItemClass Criteria
Contacts File As, First Name, Last Name, Company Name, Business Phone, Mobile Phone, Home Phone, Size
Distribution List FileAs, Number of Members, Size
Calendar Subject, Location, Start & End Date, Size
Task Subject, Start Date, Due Date, Status, Size
Note Contents, Color, Size
Mail Subject, Internet Message ID, DateTimeSent, DateTimeReceived, Sender, Size
Other Subject, DateTimeReceived
  • MailboxOnly specifies you only want to process the primary mailbox of specified users. You als need to use this parameter  when running against mailboxes on Exchange Server 2007.
  • ArchiveOnly specifies you only want to process personal archives of specified users.

Few notes:

  • When MoveToDeletedItems is specified, the Deleted Items folder will be skipped;
  • When Type is omitted or set to All, all folders are scanned, including folders like Conversation History, RSS Feeds, etc.;
  • When Quick mode is used and PidTagSearchKey is missing or inaccessible, search will fall back to Full mode;
  • For more info on PidTagSearchKey, see http://msdn.microsoft.com/en-us/library/cc815908.aspx. Note that PidTagSearchKey will have duplicate values for copied objects.
  • You need to specify MailboxOnly when running against mailboxes on Exchange Server 2007 as the Exchange 2010 personal archive options in EWSare not support in Exchange 2007 mode.

So, suppose you want to remove  duplicate Appointments from the calendar of mailbox migtester1 using attribute matching, moving duplicate items to the DeletedItems, using Impersonation and you want to generate extra output using Verbose. In such case, you could use the following cmdlet:

Remove-DuplicateItems.ps1 -Mailbox migtester1 -Type Calendar -Impersonation -DeleteMode MoveToDeletedItems -Mode Full -Verbose

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Alternative, you can use an e-mail address and specify credentials.  This allows the script to run against mailboxes in Office 365, for example:

Remove-DuplicateItems.ps1 -Mailbox olrik@office365tenant.onmicrosoft.com -Type Mail -DeleteMode MoveToDeletedItems -Mode Full -Credentials (Get-Credential) -Retain Oldest

In case you want to process multiple mailboxes, you can use a CSV file which needs to contain the Mailbox field. An example of how the CSV could look:

Mailbox
francis
philip

The cmdlet could then be something like:

Import-CSV users.csv1 | Remove-DuplicateItems.ps1 -DeleteMode HardDelete -Impersonation

Download
You can download the script from the TechNet Gallery here.

Feedback
Feedback is welcomed through the comments. If you got scripting suggestions or questions, do not hesitate using the contact form.

Revision History
See TechNet Gallery page.

Exchange PST Capture Tool released

It took a while, but today the Exchange Team released the long awaited Microsoft Exchange PST Capture Tool (initial version 14.3.16.4). The tool can be used to discover and inject PST files in an Exchange 2010 Exchange Online mailbox or archive.

The tool was originally from Red Gate and known as PST Importer. It’s architecture consists of three components: the central service, (optional) agents for PST discovery, registration and collecting PST files and an administrative console (image by Red Gate):

The online documentation can be found here.

Note that although it’s only supported for Exchange 2010 and Exchange Online, you can use it with Exchange 2007; it’s only untested (and probably unsupported) with that product.

You can read the official announcement here; you can download the tool and the agents here.

Remote PowerShell to Office 365

imageWhile trying Office 365 you might want to connect your to a remote Exchange Management Shell session instead of using the portal interface. Here’s how to proceed.

Start up a PowerShell session. The first thing we’re going to do next is store credentials in a variable for later usage:

$cred= Get-Credential

A popup will be displayed where you can enter your Office 365 admin credentials, e.g. myadminname@yourdomain.onmicrosoft.com.

Next, create a new remote PowerShell session using the following cmdlet:

$o365= New-PsSession -ConfigurationName Microsoft.Exchange -ConnectionUri https://ps.outlook.com/powershell -Credential $cred -AllowRedirection -Authentication Basic

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Next, we can import the session. However, this might be confusing since you have no context; are you creating a mailbox local or in the Office 365 environment?

The cool thing is that with Import-Session you can specify a prefix. This prefix can be specified before the cmdlet noun so that PowerShell knows which session you want the cmdlet to run against. As you probably know, cmdlets are normally constructed using <verb>-<noun> syntax, but this should be <verb>-<session prefix><noun>. When the session prefix is omitted, PowerShell assumes the current session.

For example, let’s import our Office 365 session with a prefix of “o365”:

Import-PsSession $o365 –Prefix o365

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Now, we can use that “o365” prefix before the noun. For example, to get a list of our Office 365 mailboxes, you’d use something like:

Get-o365Mailbox

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Cool and simple, eh?

Don’t forget to close your online session afterwards using:

Remove-PsSession $o365

Have fun exploring Office 365 using PowerShell.

Office 365

In case you missed it, Microsoft today announced Microsoft Office 365, Microsoft’s next-gen cloud offering, successor to BPOS. It contains Microsoft Office Professional Plus, SharePoint Online, Exchange Online and Lync online. You can watch the announcement on-demand here. Office 365, which is expected early 2011, will initially run Exchange 2010 at SP1 level.

For more information consult the Office 365′s website, consult the FAQ or follow Office 365 via Facebook (office365) or Twitter (@Office365).

You can sign up for the beta here. Note that the beta is limited and available in 13 countries only.

Exchange Online Connector for Outlook 2003

Today Microsoft released the Microsoft Exchange Online Connector for Outlook 2003 version 1.0. With this connector you can connect to Exchange Online using Outlook 2003 for free/busy lookups and to download the offline address book.

Be advised that the connector is not supported on Windows 7 or on any x64 version of Windows.

You can download the connector here.