Quick answer: The most common Outlook conversion problems are corrupted PST/OST, broken formatting or encoding, missing attachments, stalls on large files, and contacts or calendars not transferring. Fix them this way: repair the file with ScanPST first, pick a converter that preserves HTML and Unicode, verify attachments after conversion, split oversized PST/OST files, and use a PST-to-PST tool to keep contacts and calendar items.

What Goes Wrong When You Convert Outlook Data?

Outlook data conversion can present numerous challenges that affect data integrity, formatting, and usability. Understanding these potential issues and their solutions is crucial for successful email migrations and data preservation.

🎨
Formatting Loss
Critical
HTML emails, embedded images, and rich text formatting can be lost or corrupted during conversion, resulting in plain text output that loses visual appeal and important context.
⚠️ Common Impacts
• HTML signatures become plain text
• Embedded images appear as broken links
• Table layouts collapse into unreadable text
• Color coding and emphasis lost
• Company branding elements disappear
🛠️ Solutions
Use converters that specifically preserve HTML formatting and embedded content
Convert to formats like PDF or HTML that maintain visual fidelity
Test conversion with sample emails before processing entire mailboxes
📎
Attachment Loss
High
Email attachments may not transfer properly, become corrupted, or be completely lost during conversion, especially with large files or specific file types.
⚠️ Common Impacts
• Important documents become inaccessible
• File size limitations cause truncation
• Inline attachments appear as broken links
• Password-protected attachments fail to convert
• Large multimedia files get corrupted
🛠️ Solutions
Choose converters with strong attachment handling capabilities
Extract attachments separately before conversion when possible
Verify attachment integrity after conversion completion
📁
Folder Structure Distortion
Medium
Complex folder hierarchies may be flattened, reorganized, or lose their original structure during conversion, affecting email organization and workflow.
⚠️ Common Impacts
• Nested folders become flat structures
• Custom folder names get changed or lost
• Email organization becomes chaotic
• Search and filtering workflows disrupted
• Project-based email organization lost
🛠️ Solutions
Map folder structures before conversion to maintain hierarchy
Use advanced converters that preserve custom folder arrangements
Document folder structure for manual recreation if needed
🔤
Character Encoding Problems
Medium
Text encoding issues can cause special characters, accents, and non-Latin scripts to display incorrectly, particularly when converting to plain text formats like TXT or CSV.
⚠️ Common Impacts
• Foreign language emails become unreadable
• Special characters appear as question marks
• Accent marks and symbols corrupted
• Asian language support completely lost
• Contact names with special characters mangled
🛠️ Solutions
Ensure converter supports Unicode (UTF-8) encoding
Test with multilingual emails before bulk conversion
Choose formats that preserve character encoding like PST or EML
🏷️
Metadata Loss
High
Important email metadata such as read/unread status, categories, flags, importance levels, and custom properties may be lost during conversion.
⚠️ Common Impacts
• Read status indicators disappear
• Priority flags and importance levels lost
• Custom categories and color coding removed
• Follow-up flags and reminders cleared
• Email threading information lost
🛠️ Solutions
Use PST-to-PST converters to preserve maximum metadata
Document important categories and flags before conversion
Choose professional tools that explicitly preserve metadata
🔒
Protected & Encrypted Emails
Critical
Password-protected, encrypted, or rights-managed emails may be completely inaccessible during conversion, or their content may be converted as encrypted gibberish.
⚠️ Common Impacts
• Encrypted emails appear as unreadable data
• Password-protected content becomes inaccessible
• Rights-managed emails lose protection
• S/MIME encrypted messages fail to convert
• Digital signatures become invalid
🛠️ Solutions
Decrypt emails in Outlook before conversion when possible
Use enterprise-grade converters with encryption support
Maintain original PST files for encrypted content access
⚡
Why does conversion stall on large files?
High
Very large PST/OST files can cause performance problems, memory issues, timeouts, and conversion failures, especially with files approaching or exceeding size limits.
⚠️ Common Impacts
• Conversion process becomes extremely slow
• Memory exhaustion causes crashes
• Partial conversions with missing data
• Timeout errors interrupt processing
• System instability during conversion
🛠️ Solutions
Split large PST files before conversion using specialized tools
Use professional converters optimized for large file handling
Perform conversions on high-performance systems with adequate RAM
💀
Why does my PST or OST file fail to convert?
Critical
Corrupted PST or OST files can cause conversion failures, partial data loss, or complete inaccessibility, requiring repair before any conversion attempts.
⚠️ Common Impacts
• Complete conversion failure
• Partial data recovery only
• Corrupted attachments and formatting
• Missing folders or email ranges
• Unreliable conversion results
🛠️ Solutions
Run ScanPST.exe or professional repair tools before conversion
Create multiple backup copies before attempting repairs
Use converters with built-in corruption handling capabilities

🛡️ Prevention Best Practices

Minimize conversion challenges with proactive measures and proper planning

Pre-Conversion Testing
Always test conversion tools with a small sample of your data before processing entire mailboxes. This helps identify potential issues and adjust settings accordingly.
Data Backup Strategy
Create multiple backups of original PST/OST files before any conversion attempts. Store backups on different media and verify their integrity.
Tool Selection Criteria
Choose conversion tools based on your specific needs: format preservation, metadata handling, encryption support, and large file capabilities.
File Health Maintenance
Regularly maintain PST/OST files by keeping them under size limits, running periodic scans, and archiving old data to prevent corruption.
Documentation Process
Document your current folder structure, important categories, and custom settings before conversion to facilitate manual recreation if needed.
Staged Migration Approach
For large-scale conversions, implement a staged approach: convert and verify small batches before proceeding with the complete migration.

Conversion Success Metrics

8
Major Challenge Areas
95%
Success Rate with Proper Planning
24
Solution Strategies
6
Prevention Best Practices

Related guides

For corrupted PST repair and batch conversion that keeps formatting and attachments, many readers use Total Outlook Converter.