A while ago I needed something to convert a 5GB Outlook OST file to PST format. Turned out Aspose has a good (commercial) API/library for Java to do exactly that. I had not touched Java for 10 years but got things sorted within a few hours thanks to clear instructions and good examples and docs. I just used the example and made minimal changes, nothing more.

Saving to Outlook 2013/2016 PST files is not supported

Get files below or from Releases page

Jar and wrappers:

• Main executable: ost2pst.jar (verify SHA512SUMS)
• Windows batch file: ost2pst.bat
• Linux/BSD shell script: ost2pst.sh

If you need to install Java use your OS package manager or download it here: JRE8 or alternatively JavaSE-RE-8.

• Windows: ost2pst.bat <input.ost> <output.pst>
• Linux: ost2pst.sh <input.ost> <output.pst>

Or run the jar directly: java -jar ost2pst.jar <input.ost> <output.pst>

Remember you need to have at least JRE8 installed, OpenJDK is untested but should work

C:\src\ost2pst>ost2pst.bat input.ost output.pst

OST2PST (210619)

INFO: File format is "64-bit Unicode" (23)
INFO: Loading file "input.pst" (5GB)
      Folder [00] "Public"
      Folder [01] "Inbox"
      Folder [02] "Outbox"
      Folder [03] "Sent Items"

INFO: Converting "input.pst" to "output.ost" 511MB/4751MB (11%) |

• pom.xml
• Loast2pstLoadAndConvertOSTFileCLI.java

• GitHub Aspose Email-for-Java
• docs.aspose.com Installation (Maven)
• docs.aspose.com Aspose.Email java for Eclipse (Maven)

• use Ant to 'Export', 'Java', 'Runnable JAR file' (used for ost2pst.jar)
• or alternatively use Maven to build project

Add new option that tries to read corrupted ost/pst files. See here for more info.

C:\src\ost2pst>ost2pst.bat -c broken.ost

• fixed file size formatting: programming.guide :)
• updated aspose-email lib to 21.5
• removed aspose-email submodule from git repo

• show file format info
• exits instead of trying to save outlook 2013+ files
• jar also builds in maven now

• error handling, added notice about outlook '13/16 files
• updated aspose-email lib to 20.2

• fixed (visual) error before convertion
• improved messages and progress indicator
• updated aspose-email lib to 19.12

• improved progress indicator
• updated aspose-email lib to 18.8

• Aspose.Email for Java: https://products.aspose.com/email/java
• What lead me to Aspose: http://wiki.opf-labs.org/pages/viewpage.action?pageId=25887031
• Possible alternative https://github.com/rjohnsondev/java-libpst

moved from old repo mkorthof/Aspose.Email-for-Java