File Formats: Personal Storage Tables, Messages and Emails (PST/MSG/EML)

The PST file format is used to store copies of messages, calendar events and other data items within Microsoft Software such as MS Outlook. In Microsoft Exchange Server, messages are stored on the server, Microsoft Outlook stores these messages and data items in a (.pst files) that are located on the local computer to maintain offline availability of the items. At the logical level, a .pst file has three layers: the Node Database (NDB) layer, the Lists, Tables, and Properties (LTP) layer, and the Messaging layer.these layers defines data and controls that are used to allow the mail client reach message in the folder with correct information. For more information, refer to

The MSG file format is used for MS Outlook messages when saved as files of disk. An (.msg) file is a Compound Binary File (CFBF) that is used to store numerous files and streams within a single file on disk. It is partitioned in sections which are chained using the File-Allocation-Table (FAT) system which contains Chains of sectors related to each other and a Directory that holds information for contained files with a Sector ID for the starting sector of a chain and so on. For more information, refer to Outlook Message.

The EML file format is a MIME (Multipurpose Internet Mail Extensions) file format that defines a mechanism for sending information in email. The information includes text in languages other than English using character encoding other than ASCII, and 8-bit binary content such as files containing images, sounds and movies in one single file. An Eml file is a multi-part file containing the message body itself and any attached images(base64-encoded) or attachments 'inline' with the text. Another extension for the EML files is the (.mht) extension, used to open the email message file with internet browsers. For more information, refer to MIME.

LEADTOOLS supports loading only for this format.

This format is available in selected LEADTOOLS products.

The default extensions used by this format are: .pst, .msg, .eml, and .mht.

File constants associated with this file format are:

Constant Read Support Write Support Description
Pst 24 BPP None MS Outlook Personal Storage Tables (PST)
Msg 24 BPP None MS Outlookd message (MSG)
Eml 24 BPP None Multipurpose Internet Mail Extensions (EML)

Required DLL: Leadtools.Codecs.Pst.Dll, Leadtools.Codecs.Rtf.Dll, Leadtools.Codecs.Htm.Dll, Leadtools.Codecs.Txt.Dll, Leadtools.Codecs.Cmp.Dll, Leadtools.Codecs.Gif.Dll, Leadtools.Codecs.Png.Dll. For a listing of the exact DLLs needed, based on the toolkit version, refer to Files To Be Included With Your Application. Related Formats: RTF - Rich Text Format, HTM - Hypertext Markup Language.

Platform Support

Extension Module Value Win32 Win64 Net32 Net64 Linux Android Apple UWP MimeType Friendly Name
Pst PST 385 application/ PST - Outlook Format
Msg MSG 386 application/ MSG - Outlook Format
Eml EML 387 application/ EML - Outlook Format

For a complete list for supported file formats, see Summary of All Supported File Formats.

For details of the file formats supported across products and platforms, refer to File Format Comparison Chart.

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