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DataNumen Exchange Recovery

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Q: What's DataNumen Exchange Recovery?

A: DataNumen Exchange Recovery(DEXR) is the best recovery tool for Microsoft Exchange offline storage(.ost) files. It uses advanced technologies to scan the orphaned or damaged offline storage files(.ost) and recover your mail messages, folders, posts, appointments, meeting requests, contacts, distribution lists, tasks, task requests, journals, notes, etc. in them as much as possible, so to minimize the loss in data disaster.

Q: What is the current version?

A: The current release version of DEXR is 7.1.

Q: What are the new features in DEXR v7.1?

A: See history.txt under the DEXR installation directory for detailed version history and new features in DEXR v7.1.

Q: Where can I download the newest version of DEXR?

A: You can download the newest version of DEXR at

Q: Which type of Microsoft Exchange offline storage(.ost) files can DataNumen Exchange Recovery recover?

A: DataNumen Exchange Recovery supports to recover Offline storage(.ost) files for Microsoft Exchange Server 5.0 to 2019, Outlook 97 to 2019 and Office 365 OST files.

Q: When I start the recovery process, I get the error message "Either there is no default mail client or the current mail client cannot fulfill the messaging request. Please run Microsoft Office Outlook and set it as the default mail client." and DataNumen Exchange Recovery quits at once. How to solve this issue?

A: DataNumen Exchange Recovery requires Microsoft Outlook to be installed and set as the default e-mail client on the computer.

To solve this issue, please:

1. Install Microsoft Outlook on your computer if it has not been installed yet.

2. Set Outlook as the default e-mail client on the computer. To do this, follow these steps:

2.1 Start Microsoft Internet Explorer.

2.2 On the Tools menu, click Internet Options.

2.3 Click the Programs tab.

2.4 In the E-mail box, click Microsoft Outlook.

2.5 Click OK to close the Internet Options dialog box.

3. Restart DataNumen Exchange Recovery to recover your OST files.

Q: When recovering the OST file, I get the error message in the recovery log "Error 6: Cannot create destination PST file. xxxxxxx. If you have Outlook 2000 or earlier versions installed, please make sure it is installed in the Corporate or Workgroup mode. For Outlook 2002 and later versions, please make sure Exchange Server components are not installed on the current computer. You may also refer to the faq in the help document for the detailed information.". How to solve this issue?

A: This error occurs when the MAPI subsystem on your computer is not installed or configured correctly. Please refer to error 6 for more detailed information and solution.


Q: I failed to recover my Microsoft Exchange offline storage(.ost) file with DataNumen Exchange Recovery, why?

A: Contact with our technical support: If possible, please also save the recovery log into a file(make sure the "Include System Information" option in the save file dialog is selected) and attach it in your e-mail.


Q: How to order the full version of DataNumen Exchange Recovery?

A: The demo version will output a recovered PST file containing all the recovered messages and other items, with the actual contents in them filled with a demo information. To get the actual data in the messages and other items, you need to order the full version.

Please go to:

to order DataNumen Exchange Recovery. We accept all major credit cards, fax/phone orders, mail orders, and purchase orders.

If your company or institution is interested in licensing DEXR for several users, you can save a lot of money by purchasing a multi-user license or site license.

Q: What happens after I send in the order?

A: You will receive an email confirming your order shortly after sending the online order form. Then, within 15 minutes, you will receive a second email which contains a URL to the full version of DEXR.

If you do not get your full version, or if you've lost it, please email us at Please include your name, address, email address, and order confirmation number (if you have it). We will be happy to help you.

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