PST Migrations for Exchange Online Services

As I start my next venture, there is a new challenge in town.  How to fully automate the migration of PSTs from Legacy Exchange into Exchange Online Services.  At first glance, this solution is pretty straightforward if you want the user to only perform this as a manual process to import their PSTs into the online world.  But, the out-of-the box "Migration Online Services Migration Tools" do not migrate the following:

  • Auto-archive settings
  • Conditional formatting
  • Content for shared folders, such as RSS feeds to which the user subscribes, and shared subfolders
  • Delegated access to user mailboxes and their associated Access Control Lists (ACLs)
  • Hidden messages
  • Profiles
  • PST files
  • Search folders and subfolders
  • Signatures
  • Sync Issues folders and subfolders
  • User-customized mailbox rules
  • Views

However,one of the key requirements for this project I am working on is to provide a seamless experience for the user so that they really don't have to do anything to make this happen.  In other words, once their Mailboxes are migrated to Exchange online, their saved PST files from years back will also be brought i to Exchange Online . There will of course be exceptions that may need to be considered.  For example, what if the user has more total space in PSTs than their Online MB size will allow.  Many think of the online MB storage as "bottomless", but it there are restrictions made, say for example 5GB, it doesn't take long for a power user, or a user who has saved everything for many years, to reach those limits.  All of the above concerns will be addressed throughout my current project and will be tracked through these postings as discovery leads to the solution design.

For a starter, I will give you what resources are out there to provide a baseline source of "everything you ever wanted to know about PSTs, but weren't afraid to ask".  Additionally, for this solution design as it proceeds, we will be leveraging a third party product from C2C called PST Manager. Finally, to fully automate the process, there may be some need for custom PowerShell scripts to help futther automate the PST migration process.  As details are progressively elaborated, they will be updated on this BLOG.

How to Manage PSTs in Outlook 2002, 2003 and 2007  This article will tell you HOW TO use PST files to backup your data 

Microsoft Office (End User Friendly) - Create a file to save your information Describes to Users When and Why to use PSTs and OSTs as well as HOW TO 

Reconnect your old Outlook Data File This is the follow up step for a user to bring their saved PST files back into their new version of Outlook

How to configure the SIZE limit for PST and OST files in Outlook 2003, 2007 and 2010  There are four registry settings that allow you to limit the size of PSTs and OSTs 

How to repair an OST or PST file in Outlook If these files become damaged, you may be able to use Outlook's Inbox Repair Tool to fix them

Exchange Online Help and How-to  I am providing this as a general resource for Exchange Online Help

How to Import PST files into MSOL?

Fully Deploy your Microsoft BPOS to maximize your user experience  This also has a great link to a MUST HAVE download "Microsoft Online Services Deployment Guide"   

NOTE:  search the "Microsoft Online Services Deployment Guide" for PST and you wil run into this import message...

A common practice to reduce the size of the mailbox is to move mail items out of the mailbox to an archive (for example, a .PST file) either manually or with auto archive functionality. This practice is discouraged for two reasons:

 When the user moves the mail items back to the new Exchange Online mailbox after migration, the Exchange Online mailbox will not allow the user to reply to the mail.

....This is something we will be investigating, testing, and seeking remediation for.



Comments (8)
  1. Anonymous says:

    Outstanding Ost Recovery software which perform recovery process at high speed. It helps repair damaged or corrupted Exchange off-line folder and export them into a new PST file format. If you want to see demo version of this software, then you can access
    this site :-

  2. Anonymous says:

    Brilliant OST to PST Converter utility that is fully capable to recover/convert all corrupted OST file to PST file format and deleted items too.


  3. PST Migrations in medium and large enterprises says:

    Ingesting PST's ist just part of the needed workflow to get rid of local or centralized PST Files.

    We've published a whitepaper related to this.

    Happy reading 🙂…/FlightDeck-Exchange_2010-WhitePaper.pdf

    Best regards,


  4. HasanK says:


    Is this true !?  "…. the Exchange Online mailbox will not allow the user to reply to the mail"

  5. sesilryan27 says:

    OST/PST conversion can be performed by ost to pst converter

    OST to PST Converter Toolbox owns a lot handy solutions for conversion


  6. Ricky Mitchum says:

    Corruption in OST file leads to inaccessibility of the important items like email messages, attachments, contacts etc. Here is one best program ( ) that did a great job in our case and we successfully repaired our Outlook 2010 OST file and converted into PST file. Then, imported it into MS
    Outlook and now working fine. You may also take a look at this utility if inbuilt scanpst tool is not working for you.


  7. Ashis Kr says:

    If you are facing the difficulty of OST file corruption and want to re-solve it, you must take OST converter tool which acutely recover orphan Outlook OST file and move OST to PST file in few minutes. visit here :

    To get immediate result, you should use this utility, which allows user to restore your lost or encrypted OST files and move them into PST files i.e readable form by outlook

  8. X. Luther says:

    Agree with you mzbowe. Migration of user mailboxes on live servers was never an easy task, and I agree whatever conditions & circumstance you shared in your blog. But now day technology has become more advance where we can directly migrate data to live
    server using some tools, like

    However, I searched ‘Microsoft Online Services Deployment Guide’ after your recommendation, and just going through to see what comes.

    Will revert later..!

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