Zimbra Outlook PST Import Wizard Tips

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Zimbra Outlook PST Import Wizard Tips

Sometimes you may have difficulty importing your PST with the Zimbra PST Import Wizard. This may be due to the version of your PST file (i.e. Outlook 2000), the condition of your PST file, or emails with unusually large attachments. Here are a few tips that might help solve some sticky PST import problems.

Outlook Version

  • You must have Outlook XP or 2003 installed on the machine you are running the Import Wizard on (ideally Outlook 2003). Outlook 2000 and earlier is not supported. If you can't locate a machine with Outlook XP/2003, then you can install Microsoft's trial version of Office 2003. The import wizard does not actually load Outlook during the conversion, but does access some of its libraries therefore it must be installed.


  • Make a backup of your PST file! If you are going to use your old Outlook 97-2002 PST to do the import, loading your old PST with Outlook 2003 may make it not work again with older Outlook versions.

Re-exporting your PST

  • You may need to re-export your old PST to a new Outlook 2003 PST. This will clean up any inconsistencies and make the import wizard's job much easier. This may be particularly the case if your PST came from Outlook 2000 and earlier.

Message size limitations

  • By default, the importer (as of version 3.0.1) has a 10MB limit on encoded message size and is controlled by the importer itself, not the Zimbra server. Do not confuse this with Outlook's reported attachment size. A file with a 8MB attachment will encode to an email over 10MB in size and will therefore not be imported.

(e.g. a 12MB message = 16MB encoded, a 14MB message = 19MB encoded)

  • The 10MB message limit can be adjusted by adding a registry key to the Windows machine running the Import Wizard. The key/value is:
  • In REGEDIT, Add a key called:
  • Add a DWORD Value called MaxAttachSizeMB and assign it a value in MB.

(e.g 15 = 15MB). The next time the Import Wizard runs, it will use this value.

Repairing your PST

  • Use SCANPST.EXE on your PST before hand to clean up any problems with your PST before you import. You can find SCANPST.EXE by searching for it in Windows.
(START => Search => For files or folders)

RAM Requirement

  • Importing PSTs with large attachments requires a lot of physical RAM in the Zimbra server. It is best that you have the minimum required RAM according to the Zimbra specs (1GB). However you may be able to import most or all of your messages with less. An email with a 14MB attachment will not import to a machine with 768MB of RAM and standard heap settings. If you really must live with less physical RAM, a temporary workaround for migration purposes is to increase the Tomcat/Java heap size on the server. The heap size defaults to 30% of all available physical RAM. You can increase that percentage by using the following commands on the Zimbra server (logged on as the zimbra user):
$ tomcat stop
$ zmlocalconfig -e tomcat_java_heap_memory_percent=40
$ tomcat start

WARNING: Remember to set the heap size back to 30 after you are done!

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