We're sorry Aspose doesn't work properply without JavaScript enabled.

Free Support Forum - aspose.com

Outlook 2013 OST file format

Read in another post that Outlook '2013 OST files were not supported due to a major change in OST file format between '2013 and earlier versions.

Is that still the case?

Hi Karl,

Thank you for writing to Aspose support.

The issue is logged as NETWORKNET-34087 in our issue tracking system for implementation and is still not fixed. I have requested development team to provide an update about the latest status and will share the information here with you once the feedback is available.

Thanks. Would you know

#1 - With current functionality if it’s possible to identify which version of Outlook created the OST file (i.e. pre O’2013 or O’2013 specifically)

#2 - When the new capabilities are available - will it possible to identify what email account type was the source for the OST file (EAS, Imap, Exchange etc)

Hi Karl,

1. There is no such possibility to determine which version of Outlook was used to create the OST.

2. We have further tried to investigate if it is possible to provide support for OST 2013 format, but I am afraid to share that open specifications of 2013 OST format is still not available, nor Microsoft has any such intentions in the near future as can be found in this MSDN link. Since this thread has been linked with the logged issue, we’ll update you here once the specifications are available and this feature is supported by Aspose.Email API.

Hi Kashif Iqbal,

This article should help Aspose support Outlook 2013+ OST files:


Can the Aspose Development team please take a look at this article, and provide feedback on the possibility of supporting the 2013 format?

Thank you and best regards.


Thank you for sharing the information. We have forwarded this information to our Product team for their consideration. The issue has been scheduled to be investigated at our end for next month’s version. We’ll update you here once there is some information available in this regard.

Hi Kashif Iqbal,

We eagerly anticipate an update on the status of adding ability to read Outlook 2013+ OSTs. We will be able to renew our annual agreement if Aspose.Email can support this.

Would Aspose's Development team please provide an update on supporting the new format?

Thank you and best regards,

Hi Evaw,

Our Product team is currently looking into this issue at priority and investigating the possibility of support for this feature. The investigation will soon be concluded and update will be shared with us for letting you know. We’ll update you here once the feedback is available in this regard.

Hi Kashif Iqbal,

I'm glad to see Aspose.Email is now supporting Outlook 2013+ OSTs. I'be been checking this thread for an announcement almost every day :)

I'm happy the 2013 OST format information was helpful.

Thank you and best regards,

Where did you see the announcement that OL '2013+ .ost files are now supported? Which library version includes this?

HI Karl,

Please check our product release notes here:


Please note that at present, the API support for writing to OST 2013/2016 is not supported, and only reading is supported. Please try this latest version of Aspose.Email for .NET 6.2.0 and let us know your feedback.

Hi Evaw,

Thank you for sharing your feedback. Considering a number of requests for providing support for OST 2013+ formats, our Product team was always willing to implement this feature. But the feature was pending due to unavailable specifications. After receiving the valuable information, our Product team was able to implement the support for this feature.

We are glad to hear your feedback and if you face any issue related to the API, please feel free to write to for further assistance.

Outstanding!! Thanks for the link - somehow missed the update notes when I checked before posing the question.

The issues you have found earlier (filed as EMAILNET-34087) have been fixed in this update.

This message was posted using Notification2Forum from Downloads module by Aspose Notifier.