Reader Faisal asks about retrieving a list of the top 30 mailboxes in order of size.

Finding the top (or largest) mailboxes in the Exchange Server organization is a fairly common requirement. I’m often asked to produce such lists by managers when issues of server capacity get raised.

In fact, it is why I wrote the Get-MailboxReport.ps1 script, which I recommend you download.

But, in the interests of learning about PowerShell, let’s also take a look at doing it manually. Fortunately this is quite a simple report to generate using PowerShell.

You might already be familiar with the Get-MailboxStatistics cmdlet, for example:

[PS] C:\>Get-Mailbox Alan.Reid | Get-MailboxStatistics

DisplayName ItemCount StorageLimitStatus        LastLogonTime
----------- --------- ------------------        -------------
Alan Reid   608               BelowLimit 6/27/2012 5:11:15 AM

Get-MailboxStatistics returns an object made up of various properties that describe the mailbox statistics for the mailbox. We can take a closer look at these properties using Get-Member.

[PS] C:\>Get-Mailbox Alan.Reid | Get-MailboxStatistics | Get-Member

   TypeName: Microsoft.Exchange.Data.Mapi.MailboxStatistics

Name                    MemberType   Definition
----                    ----------   ----------
Clone                   Method       System.Object Clone()
Dispose                 Method       System.Void Dispose()
Equals                  Method       bool Equals(System.Object obj)
GetDisposeTracker       Method       Microsoft.Exchange.Diagnostics.DisposeTracker GetDisposeTracker()
GetHashCode             Method       int GetHashCode()
GetProperties           Method       System.Object[] GetProperties(System.Collections.Generic.ICollection[Microsoft....
GetType                 Method       type GetType()
SuppressDisposeTracker  Method       System.Void SuppressDisposeTracker()
ToString                Method       string ToString()
Validate                Method       Microsoft.Exchange.Data.ValidationError[] Validate()
PSComputerName          NoteProperty System.String
RunspaceId              NoteProperty System.Guid RunspaceId=8da06b60-9483-4d24-9930-13567c0fd94e
AssociatedItemCount     Property     System.Nullable`1[[System.UInt32, mscorlib, Version=, Culture=neutral, P...
Database                Property     Microsoft.Exchange.Data.ObjectId Database {get;}
DatabaseName            Property     System.String DatabaseName {get;}
DeletedItemCount        Property     System.Nullable`1[[System.UInt32, mscorlib, Version=, Culture=neutral, P...
DisconnectDate          Property     System.Nullable`1[[System.DateTime, mscorlib, Version=, Culture=neutral,...
DisconnectReason        Property     System.Nullable`1[[Microsoft.Exchange.Data.Mapi.MailboxState, Microsoft.Exchang...
DisplayName             Property     System.String DisplayName {get;}
Identity                Property     Microsoft.Exchange.Data.Mapi.MailboxId Identity {get;}
IsArchiveMailbox        Property     System.Nullable`1[[System.Boolean, mscorlib, Version=, Culture=neutral, ...
IsQuarantined           Property     System.Boolean IsQuarantined {get;}
IsValid                 Property     System.Boolean IsValid {get;}
ItemCount               Property     System.Nullable`1[[System.UInt32, mscorlib, Version=, Culture=neutral, P...
LastLoggedOnUserAccount Property     System.String LastLoggedOnUserAccount {get;}
LastLogoffTime          Property     System.Nullable`1[[System.DateTime, mscorlib, Version=, Culture=neutral,...
LastLogonTime           Property     System.Nullable`1[[System.DateTime, mscorlib, Version=, Culture=neutral,...
LegacyDN                Property     System.String LegacyDN {get;}
MailboxGuid             Property     System.Guid MailboxGuid {get;}
MailboxTableIdentifier  Property     System.String MailboxTableIdentifier {get;}
MapiIdentity            Property     Microsoft.Exchange.Data.Mapi.MapiObjectId MapiIdentity {get;}
MoveHistory             Property     System.Object MoveHistory {get;}
ObjectClass             Property     Microsoft.Exchange.Data.Mapi.ObjectClass ObjectClass {get;}
OriginatingServer       Property     Microsoft.Exchange.Data.Fqdn OriginatingServer {get;}
ServerName              Property     System.String ServerName {get;}
StorageLimitStatus      Property     System.Nullable`1[[Microsoft.Exchange.Data.Mapi.StorageLimitStatus, Microsoft.E...
TotalDeletedItemSize    Property     Microsoft.Exchange.Data.Unlimited`1[[Microsoft.Exchange.Data.ByteQuantifiedSize...
TotalItemSize           Property     Microsoft.Exchange.Data.Unlimited`1[[Microsoft.Exchange.Data.ByteQuantifiedSize...

Of particular interest if we want to find the largest mailboxes is the TotalItemSize property. We can sort on that property using Sort-Object, and then use Select-Object to only return the top X number of results.

As a one-liner this breaks down as follows:

  • A Get-Mailbox or Get-MailboxDatabase depending on the scope of our investigation
  • The output from either of the above cmdlets piped into Get-MailboxStatistics
  • The output from Get-MailboxStatistics piped into Sort-Object
  • Select-Object to return only the desired number of results, and optionally to return only the specific properties we want to see in our final output
  • Optionally again, an export to file

Example #1 – Select top 30 mailboxes by totalitemsize

[PS] C:\>Get-Mailbox -ResultSize Unlimited | Get-MailboxStatistics | Sort-Object TotalItemSize -Descending | Select-Object DisplayName,TotalItemSize -First 30

DisplayName                                                 TotalItemSize
-----------                                                 -------------
Administrator                                               3.495 MB (3,665,004 bytes)
Alan Reid                                                   2.893 MB (3,033,472 bytes)
TestMB HO                                                   1.818 MB (1,906,318 bytes)
Help Desk                                                   1.795 MB (1,882,379 bytes)
Test Mailboxey                                              1.659 MB (1,739,954 bytes)
TestMB BR                                                   1.657 MB (1,737,479 bytes)
Alannah Shaw                                                1.291 MB (1,353,920 bytes)
Diane Hall                                                  1.278 MB (1,339,655 bytes)
Melanie Thomas                                              1.235 MB (1,294,958 bytes)
Charlotte Bonsey                                            1.233 MB (1,293,409 bytes)
Chris Majumdar                                              1.218 MB (1,277,482 bytes)
Caroline Ball                                               1.213 MB (1,271,477 bytes)
Jane Martin                                                 1.206 MB (1,264,527 bytes)
Ferzana King                                                1.206 MB (1,264,310 bytes)
Hilary Greenall                                             1.192 MB (1,250,258 bytes)
Alex Heyne                                                  1.185 MB (1,242,700 bytes)
Sue Chandarana                                              1.177 MB (1,234,595 bytes)
Ana Williams                                                1.174 MB (1,231,015 bytes)
Hasu Janjuh                                                 1.173 MB (1,229,980 bytes)
Davina Nsiah                                                1.169 MB (1,225,418 bytes)
Valerie Andrews                                             1.168 MB (1,224,599 bytes)
Michael Phillips                                            1.167 MB (1,223,914 bytes)
Bob Winder                                                  1.166 MB (1,222,496 bytes)
Sandra Watson                                               1.164 MB (1,220,810 bytes)
Michelle Stevenson                                          1.164 MB (1,220,166 bytes)
Andrea Sharma                                               1.163 MB (1,219,437 bytes)
Hilary Seaman                                               1.161 MB (1,217,606 bytes)
Joy Singh                                                   1.16 MB (1,216,872 bytes)
Yvonne Bardall                                              1.154 MB (1,210,163 bytes)
Sue Andress                                                 1.153 MB (1,209,401 bytes)

Example #2 – Select top 100 mailboxes by totalitemsize and export to CSV file

[PS] C:\>Get-Mailbox -ResultSize Unlimited | Get-MailboxStatistics | Sort-Object TotalItemSize -Descending | Select-Object DisplayName,TotalItemSize -First 100 | Export-CSV top100mailboxes.csv

The resulting CSV file:

PowerShell Tip: Get a List of the Top Exchange Server Mailboxes by Size

Hopefully that answers your question Faisal, but once again you’re welcome to download and use the Get-MailboxReport.ps1 script for this type of mailbox size reporting.

About the Author

Paul Cunningham

Paul is a former Microsoft MVP for Office Apps and Services. He works as a consultant, writer, and trainer specializing in Office 365 and Exchange Server. Paul no longer writes for


  1. matan

    Hi, i’m trying to generate a list of mailboxes by their size from a SPECIFIC DAG or from a list of specific databases.
    any ideas?

  2. Alex

    How to get the mailbox databases with a default quota usage as 2GB sorted based on the mailbox count of the database. Any Idea…

  3. waheed saleh

    how can i Get a List of the Top Exchange Server Mailboxes by Size + alias

  4. Ederson Caminski

    Muito obrigado! Mestre Jedi!

  5. Ovi

    What about getting top 25-50 and for each creating a new-move request?

  6. Aldo

    Thank you Paul for sharing your knowledge.

    Do you know why , if I run the script on my server, the TotalItemSize is displayed in Byte and not in MegaByte ??

  7. Amin

    Great article!

    Quick question: how should I script out top 10 mailboxes that do not have archive enabled?

  8. Jim Blunt

    Hey Paul…love the site and all your hard work! Keep it up.

    Just wanted to say that I looked everywhere to try and figure out how to do this by reading in a list of users from a text file. I couldn’t find anything, so I finally sat down to figure it out myself.
    The first part is easy. Just do this:

    $UserList = Get-Content ‘C:\Temp\Users.txt’

    It took me a while but I finally figured out the second half of it:

    $Values = ForEach ($User in $UserList) {(Get-Mailbox -Identity $User | Get-MailboxStatistics) | Select DisplayName, TotalItemSize, ItemCount}

    Now I can sort it based on any one of the values by doing this:

    $Values | Sort TotalItemSize -Descending | FT -AutoSize

  9. Henry

    Hi Paul,

    Is it possible to have a PowerShell script to capture the top 10% of all user mailbox and their associated database to a table?

    Currently I have to manually find their associated database after get the top 10 result.


  10. MarceloMaulen

    Hi Paul,
    How to get space usage statistics per year by each mailbox database?

    1. Avatar photo
      Paul Cunningham

      Can’t do it with any of the builtin PowerShell cmdlets, but you can use EWS to pull the age of items and summarise them into per-year stats. Look at Glen Scales blog for lots of EWS code samples.

  11. O365Admin

    Hi Paul,

    when connecting to Office 365 and checking user mailbox size the script does not return the sort order as it does with OnPremise Exchange.

    Get-Mailbox -ResultSize Unlimited | Get-MailboxStatistics | Sort-Object TotalItemSize -Descending | Select-Object DisplayName,TotalItemSize

    Do you have a solution for that?

    1. Avatar photo
      Paul Cunningham

      As I understand it, it’s because in a remoting session the results come back with that attribute as a string, which sorts differently. I have a script that isn’t ready to share yet that converts the strings to KB/MB/GB values for sorting. I don’t know if it’s the best solution.

      1. Barry

        Just spent a while trying to get this to run remotely and then finally scrolled down this far to find the answer! If anyone else gets this far follow Paul’s advise above and run this ON THE SERVER no via a remote session!

  12. Shell M.

    Hi, my Exchange 2007 server is old and all we have. Is it ok to run the command for the get top 30 mailboxs without impact on the server? Please advise.

    Thank you

    1. Avatar photo
      Paul Cunningham

      Install the Exchange management tools on your workstation or an admin server, and run it from there. Shouldn’t impact server at all that way.

  13. Lars Panzerbjørn

    Nice beginning, but the script doesn’t really do what’s promised.

    90mb mailboxes are listed before 3gb mailboxes.

    I realise this isn’t your fault, but it is problematic…

    1. Avatar photo
      Paul Cunningham

      Are you using PS Remoting or are you using the Exchange Management Shell?

  14. Chris

    When I run this command I receive the error “The total data received from the remote client is exceeded allowed maximum. Allowed maximum is 524288000” This seems to be a hard coded limit. I would appreciate any suggestions that you have for splitting this up so I can successfully retrieve the top 100 largest mailboxes from a 20,000 user environment.

    Many Thanks Chris

  15. Styler C


    I get the following on EAC when trying to run the following

    WARNING: The object blueturtle.local/Users/CAS_{3128192dfd6a4100} has been corrupted, and it’s in an inconsistent
    state. The following validation errors happened:
    WARNING: Database is mandatory on UserMailbox.
    WARNING: Database is mandatory on UserMailbox.

    Is this an issue i should be concerned about?

  16. Adeel

    Hi Paul,

    I have a group in Active directory and each member having mailbox, I would like to get the mailboxsize for that group. Is there any command I can get the the mailbox size for the members added to that group.


  17. Philip

    hi paul,

    I am running MSX 2007 SP1 on a windows 2008 enterprise box.

    I need help in getting an excel report that will display

    Display Name Primary SMTP Item Count Total Item Size

    in descending order of “total item size”

    Additionally I want to add a filter to get only of a specific accepted domain mailboxes to show in the output.

    Kindly help me generate this report.

    Thank You

  18. oldadmin

    Using Power Shell is like moving from windows back to cmd line….any idea why MS wants to regress? cmd line does not do anything except slow people down…useless

    dear power shell….thank you for encouraging me to learn something that will perish in the future….here goes more useless info to forget later….

    knowledge from msdos, win95-98-2k-xp-server 2k-2k3…RIP…

    1. Lars Panzerbjørn

      Heh, a late reply ,, but I couldn’t help myself…
      Enjoy creating 100 users and mailbox with the GUI.
      I’ll do it in 20 seconds through PowerShell, and take the rest of the day off…

      PowerShell is moving forwards into the future. Some of us never stopped using the power of the command line…

  19. Ciro

    Hello, thanks for your support. I have a question: in my Exchange organization, i have more domains and the query it extract it give me only one domain, the principal. How i can extract all mailbox for all domains?

    1. Ciro

      I solve it!!! if you add to Get-Mailbox the option -DomainController DC01, where DC01 is the domain controller for the domain that we want extract mailbox size, we obtain the list only for that domain.

      [PS] C:\>Get-Mailbox -DomainController DC01 -ResultSize Unlimited | Get-MailboxStatistics | Sort-Object TotalItemSize -Descending | Select-Object DisplayName,TotalItemSize -First 100 | Export-CSV top100mailboxes.csv

  20. Siddu

    Hi Paul,

    How to get data of all mailboxes sizes which are having more than 900 MB in size.

    Thanks in advance.

    1. Shiva Sharma

      Problem is, Get-MailboxStatistics output just a display name – not unique and cant really be used as such. The other half of the information you need is in Get-Mailbox :- found answer in following link. once you have the data on all your mailboxes, and the output can be IMPORTED into excel you can do all your sorting etc and delete whatever you dont want

      ***if this is what you were looking for, please click this link and give the guy some credit.. i didnt come up with this, i just found it


      $Mailboxes = Get-Mailbox -ResultSize Unlimited
      foreach ($Mailbox in $Mailboxes)
      $Mailbox | Add-Member -MemberType “NoteProperty” -Name “MailboxSizeMB” -Value ((Get-MailboxStatistics $Mailbox).TotalItemSize.Value.ToMb())
      $Mailboxes | Sort-Object MailboxSizeMB -Desc | Select PrimarySMTPAddress, MailboxSizeMB

      #REM – to export this out — do the following 😉 enjoy (see the part where it says “Select” you can add additional fields like ALIAS etc to this)

      $Mailboxes = Get-Mailbox -ResultSize Unlimited
      foreach ($Mailbox in $Mailboxes)
      $Mailbox | Add-Member -MemberType “NoteProperty” -Name “MailboxSizeMB” -Value ((Get-MailboxStatistics $Mailbox).TotalItemSize.Value.ToMb())
      $Mailboxes | Sort-Object MailboxSizeMB -Desc | Select PrimarySMTPAddress, MailboxSizeMB | Export-Csv -NoType “C:tempMailboxessize.csv”

  21. Roy Simmons


    This is great information. I found what I needed by concatenating information from another resource and your examples here. What I needed was the top mailboxes sizes in a specific database. Sometimes a database gets much larger than the others. I look for the largest mailboxes and then move them to a younger database. This is what I came up with:

    Get-MailboxDatabase “yourDBnameHere” | Get-MailboxStatistics | Sort totalitemsize -desc | Select-Object DisplayName,TotalItemSize -First 30

  22. Nodorina


    Is there a way to combine Get-Mailbox & Get-MailboxStatistic?

    We are after:
    The DisplayName, LastLogonTime from Get-MailboxStatistic. &
    ForwardingAddress, ProhibitSendReceiveQuota from Get-Mailbox.

    Instead of generating two different report, is there a way to combine these parameters from two different cmdlets into one report?


  23. Richard

    Thanks Paul. I will give it a try

  24. Richard

    I tried .get-mailboxreport.ps1 –database foxboro1 to export all mailbox name from database, but i got an error
    get-mailboxreport.ps1 is not digitally assigned! can you please help
    I just need to export mailbox names within certain database with mailbox size


  25. Tri Pham

    Can I query for these values OldestItemReceivedDate & NewestItemReceivedDate in Get-MailboxStatistics?

    1. Avatar photo
      Paul Cunningham

      Get-MailboxFolderStatistics has some parameters for collecting that info.

  26. Leng

    Big fan,another great work Paul!

  27. Billy Shepherd

    Thanks for the great info, Paul. I always look to you first when I need to know/learn how to do something in Exchange and PowerShell

  28. Rene

    Hi Paul,

    I have an exchange 2003 with all the boxes and a new Exchange 2010 and i did the command on the 2010 and the result was great but do not include the 2003 servermail boxes infos…
    Is there a way to add them simply on the same script ?


  29. Wasim Ahmed

    Hi Paul,

    Where does the “csv” file goes to after running this command……….

    Get-Mailbox -ResultSize Unlimited | Get-MailboxStatistics | Sort-Object TotalItemSize -Descending | Select-Object DisplayName,TotalItemSize -First 100 | Export-CSV top100mailboxes.csv


    1. Avatar photo
      Paul Cunningham

      It will be written to the same folder you’re in when you run the command.

  30. Rebecca Hope


    I am trying to find a command that will return the user and total item count for the inbox only.

    Can this be done?



  31. 0xG

    Close, but no cigar. The info for “Microsoft.Exchange.Data.Mapi.MailboxStatistics.TotalItemSize” indicates that it is of type “Microsoft.Exchange.Data.Unlimited”.

    This is a problem, because sometimes the value is the string “unlimited”, sometimes GB, sometimes MB, and usually displayed in a way that does not lend itself to importing into Excel.
    (Having both the string, MB and unit count in the same column is very poor.)

    So what .Net methods can we invoke to return just a plain byte count?

  32. Ahmed

    hi Paul
    i have use these PS command and got the desire result, but in addition to DISPLAY NAME i want add another Attribute like UserlogonName when exacting the result, i did that with UserLogonName but i unable to fetch the UserLogonName attribute.

  33. Shane Bryan

    Thanks Paul 🙂

Leave a Reply