For reliable results in your archive



Please see the announcement on the Home Page.

A list of customer’s frequently asked questions. OTA refers to Outlook True Archive throughout.

Is there a quick introduction on the basics of Outlook True Archive?

Yes. Follow this link to see a Flash tutorial of about 65 seconds – you will be up and running after that! (395k, opens a new window and uses Flash.)

How can I create a new PST (and what is it)?

Click on the ‘*’ button beside the list of destination archives. A .PST file is a store for your mail and other items created by Outlook. The identical file format is used by Outlook True Archive to hold the emails, calendar items, etc. you have selected to archive.

Tutorial video: To see a short demonstration of how to create a new PST file, click here. (120k, opens a new window and uses Flash.)

Where does Outlook True Archive store my archived mails?

Outlook True Archive will archive your emails in the archive file in the ‘Destination’ section of the main Outlook True Archive screen. (See Screenshots and select “Create archive”.)

How can I access my archived mails?

After you archive your emails to a PST file, you can easily open them in Outlook in the same way as your non-archived mails.

I have archived my mails but I do not see a way to select them in Outlook.

In Outlook, select “View” and ensure “Navigation Pane” is selected.

Tutorial video To see a short demonstration of how to view your archived items in Outlook, click here. (110k, opens a new window and uses Flash.)

How can I tell OTA to always backup email more than 1 year old?

Click on the “Configure” button. Select the appropriate period for the “Archive mail older than” setting. Each time you start OTA it will automatically calculate the appropriate end date for the period you set.

Why is my unread mail not being archived?

Make sure you have selected “Include unread messages” in the “Content Filter” area before starting the task.”

Does OTA preserve the folder structure of Outlook?

Yes. OTA will try to recreate your folder structure in the destination PST.

Can I make a copy of my email rather than archive it?

Yes. Select “Copy Messages” in the Task dropdown list.

Some users have reported they have used this option, while they learned about the many options available in Outlook True Archive. (Easier to delete a copied mail than recover a mail deleted by accident.)

Can I archive mail based on a keyword search?

Yes. Click on the “More” button in the “Content Filter” area and enter the keywords in the “Body Contains” field.

Can I just archive mail that has large attachments?

Yes. In the “Content Filter” area select an appropriate attachment size for the “Attachments” setting.

How large can a PST file be / is there a limit on PST file size?

Microsoft has set three types of limits on the size of a PST file:

  1. For Microsoft Outlook 2002 and earlier the maximum PST file size is 2 Gigabytes (GB). PST files are in the ANSI format.
  2. For Microsoft Outlook 2003 and later, the maximum default PST file size is 20GB. PST files are stored in the Unicode format.
  3. For the (very) brave and technical, you can choose to override the 20Gb PST file limit, according to Microsoft. Click here for more information. (Link opens new browser window / tab.)

Remember: Your file system also applies a limit, so if you still use FAT16 or FAT32 or (as opposed to NTFS) on the storage device holding or archiving your PST (or OST), be mindful of the maximum file size your storage device operating system allows.

Microsoft’s limits (described above) will apply when moving/copying emails during an archive or copy task in Outlook True Archive. If your archive PST file has reached the maximum file size the best option is to create another archive PST file and use the new (empty) file as your new destination PST in Outlook True Archive.

Background: Read more about Microsoft’s file size limits by clicking here.

How do I just archive mails with high importance?

Yes. In the “Content Filter” area click the “More” button and in the “Importance” dropdown select “High”.

Will OTA ignore folders that I have marked as “Do not archive” in Outlook?

No. OTA cannot currently determine which folders you may have excluded from archiving in Outlook. Instead deselect the appropriate folders in the folder tree and make sure that OTA is set to remember your selections.

Will OTA remember the folders I have selected?

Yes. By default OTA automatically selects all folders within a PST for backup. You can change this by clicking the “Configure” button and selecting the appropriate setting for “Folder selection”

Can I export my mail in EML (or another) file format?

Yes. First make sure that EML is selected as the export format. To do this click the “Configure” button and then select the “Folder Export” tab. Make sure “EML” is selected for the “Export format” setting and then close the Configuration dialogue. Select “[Disk Folder]” as the destination archive, then select the folder on your disk in which to save the EML files.

Tutorial video To see a short demonstration of how to export to a disk folder in various formats, click here. (460k, opens a new window and uses Flash.)

If I export messages to a disk folder will attachments be preserved?

Yes, if you export in EML or MSG format, then attachments will be preserved.

What are the different Archive tasks?

In the Task dropdown menu there are four different options you can select:

  • Archive Messages will simply move the messages to the destination location you have selected.
  • Copy Messages will create a copy of the selected messages in the destination location whilst keeping the original copy in your source PST.
  • Delete Messages will remove the selected mails from your PST file. For more options on deleting mails, click on the ‘Configure’ button, select the ‘Advanced’ tab and click on the ‘Delete Task’ drop down menu.
  • Update Timestamp will change the “Last Modified” timestamp of the selected mails to the current time and date. This is an advanced task and should only be performed if you are sure that you need to change the timestamp. For more information see “Microsoft Outlook and the Last Modified timestamp”

Can I use Outlook True Archive to archive items in my OST file?

Outlook True Archive may be used to archive, copy and delete items in your OST file. However it must be noted that using Outlook True Archive to perform date/timestamp changes on items in your OST file is not currently supported.

Can I use OTA to archive items in my Exchange mailbox?

Outlook True Archive may be used to archive, copy and delete items in your Exchange mailbox. However you cannot use Outlook True Archive to perform date/timestamp changes on items in your Exchange mailbox.

Which versions of Outlook does Outlook True Archive support?

Based on our testing and feedback from customers, Outlook True Archive has worked with all versions of Outlook (since Office 2003) encountered so far, so long as they are the 32-bit version.

Outlook True Archive is a Windows program and as such will not work on an Apple Mac nor Linux operating system (OS).

How do I enter my registered name / license key?

Tutorial video To see a short demonstration of how to enter your registered name and license key, click here. (165k, opens a new window and uses Flash.)

OTA displays an activation error – is there an alternative way to activate the software?

This can arise where something is blocking the activation request such as anti-virus software or rules in a router or firewall. Manual activation is possible, as follows:

  1. Start Outlook True Archive
  2. Click on the grey “Configure” icon at the top right hand side to open the ‘Configuration’ screen
  3. Hold down the [Control] key and click on the license tab
  4. Enter your Registered Name and License key details and the click the ‘Manual Activation’ button.
  5. A new page will open, select ‘Activate using a web browser on this computer’ and click ‘Next’.
  6. Click on the URL link on the next page and a web page with the Installation ID pre-populated will open.
  7. Click ‘Submit’ and you are given an ‘Activation Code’.
  8. Now go back to the manual activation dialogue, click ‘Next’ and copy the activation code into the available fields (you can copy the whole code at once).
  9. Now click on ‘Activate’, (take a note of the installation ID and Activation Code for your records), and then on ‘Done’

There is a separate page for many other questions related to activation – click here.


64-bit compatibility

Windows 32-bit vs. Windows 64-bit

Outlook True Archive works with all 32-bit and 64-bit versions of Windows released since 2001, including Windows XP, Vista, 7 and 8.

Office 32-bit vs. Office 64-bit

Outlook works with 32-bit version of Office only. It does not work with 64-bit versions of Office.

If you are in any doubt, download the trial version and test for yourself.


If you are using Office 64-bit and need to archive mails and calendar events from your Outlook, you may be able to do so if you have access to another PC with Office 32-bit installed. As the PST file format is the same, you can transfer the PST to the PC with Office 32-bit installed, run Outlook True Archive on that PC and then transfer the PST (and archive file(s)) back to the original PC. Alternatively, the PST can be left on a network drive where both PCs have access. (NB: Only one PC can open a PST file at a time.)

Background on the lack of a 64-bit version

Outlook True Archive uses the Microsoft API calls to open the PST file(s) which include your mails and calendar items to be archived. The software tools developed to do this are available in 32-bit versions but not yet in 64-bit versions. Naturally, we would wish to offer a 64-bit version as soon as possible and will do so, once a tested set of the development tools is available.

The availability of a version to support 64-bit versions Office will be announced on these pages once it is released.


Command Line Switches

Outlook True Archive – Command Line Switches

Available as a PDF file – click here. (<200kb)

OTA can operate unattended via command line switches. You may find it useful to run OTA from your favourite Windows Scheduler so that archive tasks are performed at regular intervals.

Enclose all parameters in double quotation marks (ASCII 34) where parameters may include spaces, such as in file names, folder names, paths, subject selections, etc. See examples below.

The following command line parameters are available:

/Auto Perform an automated task. You must use this switch in order to run OTA in unattended mode.
/T The task to perform. Use A for Archive, C for Copy, D for Delete, e.g. /T:A
/SA The source archive. Specify the name of a PST as it appears in the “Source” dropdown list of the OTA screen. E.g. /SA:”Personal Folders”
/SF Specifies the source folder if you are archiving from a folder instead of from a PST file. E.g. /SF:”C:\MyMail\MyArchiveFolder”
/DA The destination archive. Specify the name of a PST as it appears in the “Destination” dropdown list of the OTA screen. E.g. /DA:”My Archive”
/DF The destination folder when exporting to a disk folder. E.g./DF:”C:\My Documents\Exported Mail”
/AP The archive period. This can be specified in two ways: To archive items up to a date relative to the current date, specify a number followed by d, m, w or y. For example /AP:7d would archive all items dated up   to 7 days ago. And /AP:6m would archive all items dated before the 1st of the month six months previous. /AP:2y would archive all items dated before the current date 2 years ago.

To specify an absolute date range use the format /AP:yyyymmdd-yyyymmddA. For example: /AP:19981105-20140611A would archive all items between the 5th November 1998 and the 11th June 2014.
Make sure to include the A after the second date!
/UR Include unread messages or not. Use /UR:Y for Yes, /UR:N for No
/FS Mail subject. E.g. /FS:”*invoices 2014*”
/FF “From” email address. e.g. /FF:”*@outlooktruearchive.com”
/FT “To” email address. e.g. /FT:”first.last@mydomain.com”
/SEL The selection file which specifies the folders which are not to be processed. If you do not specify a selection file, all folders will be processed.

Please note: The folder list inside the selection file is an exclusion list. Therefore any folder not listed in the SEL file will be included in the task operation.

This is especially important to note when performing a Delete task in OTA.

/FO Specifies folders to include in the task operation – all other folders will be ignored. Format is /FO:”[FolderName]”  To specify multiple folders, separate each folder name with a comma e.g. /FO:Inbox,TestFolder,Tasks

To include subfolders the complete path to the folder should be specified, e.g.:
/FO:"Inbox,Sent Items,MyFolder\TestSubFolder1, MyFolder\TestSubfolder2"
/EXF Export format when exporting mail to disk. Valid values are MSG, EML, HTML, EHTML, TNEF, TEXT. Default format is MSG
/EXP Naming   pattern for export files. Enclose value in quotes. Default is”%ct% – %su%”. Please note: when using this switch in a batch file you must use double percentage signs e.g. “%%ct%% –   %%su%%” or tilde e.g. “~ct~ – ~su~”
/DM Delete Mode. Use D for Delete, M for move to Deleted Items folder, E for permanent delete in Exchange. No warning will be given prior to execution of the delete!
/Preview Preview the task.
/TI Specifies the title of the popup which opens during an automated task. Format is /TI:”<Task Title>”
/FFS Enables filtering dependant on the colour of the Follow Up flag assigned to an Outlook item. Options are:
/FFS:CP Items marked Complete
/FFS:NC No colour flag set
/FFS:NF No flags set
/FFS:RED Red flag
/FFS:BLU Blue flag
/FFS:GRN Green flag
/FFS:ORG Orange flag
/FFS:PUR Purple flag
/FFS:YEL Yellow flag
/PFN Specifies which Outlook email profile to use when performing an automated task.  If the switch is not used OTA performs the task on the default Outlook email profile.  Format is /PFN:”ProfileName”
/PFP Specifies the password to access the profile specified by the PFN switch.  If no password is assigned to the profile this switch is not required.


/Auto /T:A /AP:6m /SA:”Personal Folders”   /DA:”My Archive” /UR:Y /SEL:”C:\Folders.SEL”
This performs an Archive task, moving mail older than 6 months from the “Personal Folders” PST to the “My Archive” PST, including unread mails. The folders.sel file determines which folders are actually processed.
/Auto /T:C /AP:1y /SA:”Personal Folders” /DF:”C:\temp” /UR:Y /EXF:MSG
This exports a copy of mail older than 1 year to the folder C:\Temp, including unread mails. The messages will be exported in MSG format. Filenames will be based on the creation time and subject of each message. All folders in the source PST are processed.
Environment variables may be used with the SA, SF, DA and DF switches.  For example, a source mailbox could be defined by /SA:”Mailbox – %username%” where username is defined as the current user’s name.



Who publishes OTA?

Please see the announcement on the Home Page.

HE Clissmann is a firm based in Dublin, Ireland, founded in 1949. We have been involved in the PC business since 1979. Our first “PC” was a North Star Horizon with 32K of RAM and two floppy disk drives, running CP/M.

What IT work HE Clissmann does now.

We develop solutions with Microsoft tools where there are none available from other developers. One example is why you are on this site – Outlook True Archive.

We have developed many other products and currently market SMSware for the sending of SMS text messages (www.smsware.com). We have a Time and Attendance product in development.

Where we are located (and what else we do).

  • We are located in our own premises south-west of Ireland’s capital, Dublin. (www.clissmann.com)
  • As part of our business, established in 1949, we distribute pharmaceutical products to hospitals and pharmaceutical wholesalers and retailers in Ireland.


User Feedback

“I have been using Outlook True Archive for over a year now and have found it to be intuitive, fast and most of all very reliable. For anyone that uses Microsoft Outlook – this is what Microsoft should have included to complete the product.”
Bryan L, Perth, Australia

Thanks for being responsive. It is very much appreciated. Most software companies ignore their Customers. It is a pleasure working with you!
Adam A, Massachusetts, USA

“I’m a lawyer and have to save every email that I send or receive. My Outlook “personal folder” was so bloated that it was constantly crashing.

Outlook True Archive allowed me to move all of my old emails out of my “personal folder” and into sorted and easily searchable archive folders. I no longer have to worry about losing all of my old emails in a corrupted “personal folder” and my Outlook is working like new again. Thanks for making OTA!”
Julian C, Illinois, USA

“Thanks indeed. A shining example of quality user support!”
Thomas M, Prague, Czech Republic

“Outlook True Archive saved me from the wrath of my IT department as I couldn’t archive mail properly with native tools due to a system migration changing the modified timestamp of all the mail in my oversized mailbox.
Thanks for a great tool that’s really easy to use.”
Glenn S, Victoria, Australia

“Outlook True Archive is a must-have tool that had already saved me dozens of hours of laborious work. As a system administrator of a 30-user network, I often need to archive my users’ mailboxes. MS Outlook’s annoying “feature” of archiving emails by their Date Modified attribute, coupled with the fact that some of our users have more than 100 subfolders nested under their Inbox, made OTA one of my all time favorite utilities. OTA makes email management a breeze!”
Dotan A, New York, USA

User comments have also contributed to our FAQ (frequently Asked Questions) Section.


OTA features

Please see the announcement on the Home Page.

Outlook True Archive features allowed you to :

  • Select the folders you wish to archive.
  • Select mail messages by date received, date sent, date last modified.
  • Move or copy matching messages to the destination, or just delete them.
  • Preserves message received & sent time stamps in destination.
  • Create an Archive .PST file if one does not exist.
  • Select source and destination for moving mail out of / back into your main PST file.
  • Choose to include or exclude unopened mail items.
  • Preview mode allows you to see totals before performing an archive.
  • Set the archive task priority to Normal, Medium or High.
  • Export messages to a disk folder in MSG format, EML, HTML, TNEF or plain text format
  • Import messages from a disk folder in MSG or TNEF format.
  • User defined filenames for message export.
  • Update the “Last Modified” time stamp of selected messages within the PST to the original received date or sent date.
  • Please note for Office 64-bit version – please see the guide in our Support section

Price 19.95 – Download a free trial or Buy Now.

Examples of practical use

You have accumulated mail over the years. It takes longer and longer to open Outlook now. When Outlook freezes the odd time, it take a long time to re-build the file.

Solution: move all mails up to -say – the end of the last quarter into an archive PST using Outlook True Archive date feature. The PST archive file can be backed up to a CD or DVD – no risk of loosing your history. Leave a copy of the archive PST on the hard disk, so that you disk index utility (like Google Desktop or MS Windows Search can easily find those older mails. And if Outlook freezes again (although this is less likely with a smaller PST as you main PST for incoming mails)? Outlook will re-build the main PST far faster than before.

You want others to be able to access your mail history – maybe a PA or maybe a team in your firm. But Outlook will only allow one user to open a PST at a time.

Solution: Archive out all the mails you want to share to individual .MSG files using Outlook True Archive and place in a shared folder on your network. By allowing access to this shared area to the right team members, they can each index and search these mails (with MS Windows Search – free) and re-open them in Outlook.

Please see the announcement on the Home Page.


About Outlook True Archive


As of April 30th 2019 our service provider for authentication of installations (aka activation) is withdrawing their service. We have reviewed the impact of their decision on our modest offering and feel we have no choice but to withdraw OTA from the market. This decision is taken with regret and has been informed by the age of the product and the tools it uses (though it still works well for current users). 

Current users have come to rely on the results produced by OTA and we plan to offer a version of the software to them without activation limits, on the basis that this last edition is used by them only and will work but will not be supported in the future.

We are saddened to “step off the stage” but this decision has been thrust upon us and we ask for your understanding.

Outlook True Archive is a Windows program that does what Outlook itself cannot do – it truly archives your mail from an Outlook PST file (or OST or Exchange server account), with great ease and predictable results.

Unlike the built-in tool, Outlook True Archive eases the process of archiving your mails and calendar items. It has a clean visual system for making selections. It automatically remembers folders you selected previously. It is easy to use, as all archiving options can be simply selected.

Click here to see a 65 second Flash demonstration of how the $19.99 utility can help you in managing your Outlook PST mail file bloat today.

For advanced users, Outlook True Archive offers a command line interface, so that tasks can be prepared by an IT-person and run systematically thereafter, either automatically or by a non-expert user.

Outlook True Archive archives mails items based on the date the mail was received or sent, rather than the date it was last modified. The benefit for you: reliable results in your archive.

Why you need this utility

Principally, our users have complimented the software for ease of use and the consistent, reliable results. The archives they create with Outlook True Archive contain exactly what they expected.

When you use Microsoft Outlook to archive a Mail message folder by date, Outlook determines the message age from the Sent timestamp, Received timestamp, or from the message’s Last Modified timestamp, whichever is later. As a result you may find that your messages are not archived because the Last Modified date/time has been updated.

The following actions will change the message’s modified date/time:

  • Forwarding
  • Replying
  • Replying to All
  • Editing and Saving
  • Moving or Copying

Copying or moving the message to another message folder does not always change the Last Modified timestamp; if the destination folder is a Personal Folders file (.pst), the timestamp does not change.

If the destination folder is an Exchange Server Mailbox or an Offline Folders file (.ost), the timestamp does change.

For Microsoft’s take on this issue please see the following knowledge base article: Message Modification Date Determines Archive Date

(Please note for Office 2010 or Office 2013 users: 64-bit version not yet supported; 32-bit works great! OTA works well on both 32-bit and 64-bit versions of Windows. See the guide in our Support section.)



Download no more


As of April 30th 2019 our service provider for authentication of installations (aka activation) is withdrawing their service. We have reviewed the impact of their decision on our modest offering and feel we have no choice but to withdraw OTA from the market. This decision is taken with regret and has been informed by the age of the product and the tools it uses (though it still works well for current users). 

Current users have come to rely on the results produced by OTA and we plan to offer a version of the software to them without activation limits, on the basis that this last edition is used by them only and will work but will not be supported in the future.

We are saddened to “step off the stage” but this decision has been thrust upon us and we ask for your understanding.

Outlook True Archive is no longer for sale.