Migrating Shared Mailboxes with CodeTwo Exchange Folders: Step-by-Step

Troubleshooting Common Issues in CodeTwo Exchange Folders

1. Synchronization fails or is slow

• Symptoms: Changes in the source mailbox don’t appear in the target folder, or sync takes a long time.
• Likely causes: Network latency, large item count, throttling on Exchange/Office 365, outdated CodeTwo service or agents.
• Fixes:
  1. Check network connectivity and latency between servers.
  2. Reduce sync load by filtering folders or date ranges.
  3. Verify Exchange/Office 365 throttling policies; request temporary throttling relaxation if needed.
  4. Update CodeTwo software to the latest version and restart sync agents/services.
  5. Review CodeTwo logs for specific errors and follow error-specific guidance from CodeTwo documentation.

2. Permission or access denied errors

• Symptoms: Operations fail with access/permission errors when accessing mailboxes or folders.
• Likely causes: Insufficient ApplicationImpersonation or mailbox permissions, expired/invalid credentials, or token scope issues in Exchange Online.
• Fixes:
  1. Ensure the service account has ApplicationImpersonation role (Exchange) and full mailbox access where required.
  2. Recreate or reauthorize the service account credentials and ensure MFA/conditional access policies won’t block automation.
  3. For Exchange Online, verify Azure AD app permissions and grant admin consent if using modern auth.

3. Duplicate items appear after sync

• Symptoms: Email items or calendar entries are duplicated in target folders.
• Likely causes: Interrupted previous sync cycles, changes to item IDs, or incorrect mapping rules.
• Fixes:
  1. Run a consistency check or deduplication tool within CodeTwo if available.
  2. Review and correct folder mapping rules to avoid overlapping targets.
  3. Re-sync only affected folders after backing up data; avoid full re-sync unless necessary.

4. Folder structure not replicated correctly

• Symptoms: Subfolders missing or created in wrong locations.
• Likely causes: Incorrect folder mapping, filters, or limitations in target mailbox structure.
• Fixes:
  1. Verify mapping rules and ensure hierarchical mapping is enabled where required.
  2. Confirm target mailbox supports the folder names and paths (special characters or length limits).
  3. Recreate missing folders manually if necessary, then re-run sync for structure only.

5. Items missing after migration/sync

• Symptoms: Expected emails, contacts, or calendar items are absent in the target.
• Likely causes: Filters excluding items, item size limits, or errors during migration.
• Fixes:
  1. Check filters (date, size, item type) applied in job configuration.
  2. Inspect CodeTwo logs for errors related to specific items and retry failed items.
  3. Increase item size limits on both source and target if smaller attachments were blocked.

6. Authentication or OAuth token expiry (Exchange Online)

• Symptoms: Jobs fail repeatedly after previously working; authentication errors reference tokens.
• Likely causes: OAuth tokens expired, app consent revoked, or conditional access policies blocking automated access.
• Fixes:
  1. Re-authorize the Azure AD application and grant required permissions with admin consent.
  2. Check conditional access and MFA policies; configure service account or app to comply.
  3. Monitor token expiry and implement automated re-auth flow if supported.

7. Performance degradation after increasing users/items

• Symptoms: Overall sync throughput drops as tenant size grows.
• Likely causes: Insufficient resources on the machine running CodeTwo, rate limits, or inefficient job configuration.
• Fixes:
  1. Scale out: distribute jobs across additional agents or servers.
  2. Optimize job configuration: segment by department, date ranges, or mailbox size.
  3. Monitor CPU, memory, and network; upgrade resources as needed.

Helpful diagnostics and maintenance steps

• Check logs: Always start with CodeTwo logs and Exchange diagnostic logs to pinpoint errors.
• Run small test jobs: Reproduce the issue on a small set of mailboxes to isolate cause.
• Back up before changes: Ensure you have backups before running fixes like re-syncs or deduplication.
• Contact CodeTwo support: For persistent or unclear errors, provide logs and job configuration for faster support.

If you want, I can provide specific command examples, log locations, or a checklist tailored to Exchange Online or on‑prem Exchange—tell me which environment you’re using.