Email, PST, OST, EML & Other File Recovery: eBooks, 3D, CAD & Database Files
This category covers the files that don't fit neatly into Documents, Photos, Video, Audio, or Archives — but are often the most critical files on a user's computer. A single Outlook PST file can contain years of business correspondence. An AutoCAD DWG file can represent months of engineering work. An SQLite database can hold an entire application's data. Each of these specialized formats has unique internal structures that affect how recoverable they are. See the complete file type overview.
Table of Contents
1. Email Files — PST, OST, MSG, EML, EMLX, MBOX
Microsoft's PST file format specification (MS-PST) documents the complete internal structure. PST/OST files are essentially miniature databases — they use B-Tree indexing to organize emails, contacts, calendars, tasks, and notes. This database-like structure means:
- Corruption in one area (a single email or contact) doesn't necessarily affect other data. SCANPST.EXE can isolate and remove corrupted entries.
- The NDB (Node Database) and BBT (Block B-Tree) provide redundancy — even if one index is damaged, the other can often reconstruct file locations.
| File | Used By | Magic Number | Typical Location | Max Size |
|---|---|---|---|---|
| PST | Outlook (POP3, IMAP archives, local folders) | 21 42 44 4E (!BDN) | Documents\Outlook Files\ | 50 GB (Outlook 2010+) |
| OST | Outlook (Exchange, Office 365 cached mode) | 21 42 44 4E (!BDN) — same as PST | AppData\Local\Microsoft\Outlook\ | 50 GB (configurable) |
| MSG | Individual saved Outlook messages | OLE2 compound document (D0 CF 11 E0) | Anywhere saved | N/A (single message) |
| EML | Windows Mail, Thunderbird, exported messages | Plain text MIME — starts with From: or Return-Path: | App profile folders | N/A (single message) |
| MBOX | Thunderbird, Apple Mail, many Linux clients | Plain text — starts with From (with space) | App profile folders | Practically unlimited |
PST/OST Recovery & Repair
After recovering a PST/OST file with XRecovery, if Outlook reports corruption:
- Run SCANPST.EXE (Inbox Repair Tool) — located in
C:\Program Files\Microsoft Office\root\OfficeXX\. Microsoft's official PST repair guide. - Always run SCANPST on a COPY of the recovered PST, never the original recovered file.
- SCANPST creates a backup (.bak) before making changes. If repair fails, the original is preserved.
2. eBook Files — EPUB, MOBI, AZW, DJVU
EPUB (Electronic Publication): W3C EPUB 3.3 standard. EPUB is actually a ZIP archive containing HTML, CSS, and images — making it structurally similar to DOCX. This ZIP-based structure gives it the same recovery advantages: individual components can be extracted even if the container is partially damaged. Magic number: 50 4B 03 04 (PK.. — same as ZIP).
MOBI/AZW (Kindle): Amazon's proprietary format based on the Mobipocket standard. Magic number: 42 4F 4F 4B 4D 4F 42 49 (BOOKMOBI). Earlier versions used PalmDOC compression.
DJVU: DjVu format — optimized for scanned documents. Uses wavelet compression for much smaller file sizes than PDF for scans. Magic: 41 54 26 54 46 4F 52 4D (AT&TFORM).
3. 3D, CAD & Design Files
| Format | Type | Magic Number | Recovery Notes |
|---|---|---|---|
| STL | Stereolithography — 3D printing standard | ASCII: solid | Binary: 80-byte header | Simple triangle mesh. ASCII version is plain text — trivially recoverable. |
| OBJ | Wavefront OBJ — universal 3D exchange | Plain text starting with # or v / f | Text-based — easy to recover. Associated MTL (material) and texture files must also be recovered. |
| FBX | Autodesk FBX — animation and 3D exchange | 4B 61 79 64 61 72 61 (Kaydara) | Proprietary binary or ASCII. Binary version harder to reconstruct. |
| BLEND | Blender — open source 3D project | 42 4C 45 4E 44 45 52 (BLENDER) | Well-documented open format. Contains all scene data in one file. |
| DWG | AutoCAD Drawing — industry standard CAD | 41 43 31 30 (AC10) versions vary | Complex proprietary binary. Multiple versions (AC1021, AC1024, AC1032). Recovery: detect header version. |
4. Database Files
Databases are complex structured files. Recovery success depends on whether the database engine uses write-ahead logging (WAL), which can enable recovery from partially corrupted files.
| Format | Engine | Recovery Notes |
|---|---|---|
| MDB/ACCDB | Microsoft Access | After recovery, use Access → Database Tools → Compact and Repair Database. This rebuilds indexes and reclaims space from deleted objects. |
| SQLITE / .DB | SQLite | Magic: 53 51 4C 69 74 65 (SQLite). SQLite includes built-in recovery: .recover command in the CLI. WAL files (.sqlite-wal) may contain recent uncommitted transactions. |
5. Other Specialized Formats
| Category | Formats | Recovery Notes |
|---|---|---|
| System & Config | LOG, REG, BAT, CMD, INI, CFG | Plain text — trivially recoverable. No internal structure to corrupt. |
| Fonts | TTF, OTF, WOFF, WOFF2 | TTF uses TrueType outline format. OTF is based on PostScript. OpenType specification. Binary but well-structured. |
| Executables & Libraries | EXE, DLL, SYS | Portable Executable (PE) format. Microsoft PE specification. Magic: 4D 5A (MZ). |
| Disk Images | VHD, VHDX, VMDK | Virtual machine disk images. Can be enormous (100+ GB). Mount first, then recover files from inside. |
6. Recover with XRecovery
XRecovery recognizes all these specialized format signatures. See the complete 1000+ format matrix.
- Download XRecovery to a different drive.
- Select the drive → Deep Scan for comprehensive signature-based recovery.
- For PST/OST: locate in Outlook Files folder. For databases: typically in AppData or project folders. Filter by file type.
- After recovery, verify file integrity: open PST with Outlook, run Compact and Repair on databases, open DWG in AutoCAD. Maximize recovery success.
- Recover to a different drive. XRecovery tutorial.
Years of Emails. Months of CAD Work. Recover Everything.
XRecovery recovers PST, OST, DWG, SQLite, EPUB and 1000+ specialized formats. Free scan.
Download XRecovery FreeFAQ
How do I repair a recovered PST file that Outlook won't open?
Run SCANPST.EXE on a COPY. Microsoft's PST repair guide. If SCANPST fails, professional Outlook recovery tools exist.
Can XRecovery find individual EML files?
Yes. EML files are plain text MIME messages. XRecovery identifies them by content pattern matching. Download.
Are SQLite databases recoverable after deletion?
Yes. SQLite has a clear SQLite format 3 header. If WAL files exist alongside, recover both — they contain recent uncommitted data. SQLite file format.
Your Outlook Emails. Your CAD Project. Recover Them.
XRecovery finds specialized files by their unique signatures. Free scan.
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