Batch Migration & Multi Threading

Batch Migration & Concurrency Guide

The Batch Migration tab enables migrating dozens, hundreds, or thousands of mailboxes concurrently in a single high-speed session with adaptive multi-threading, intelligent CSV parsing, and enterprise cloud authentication.

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⚡ Concurrency & Worker Scaling

Mundofy MailMigrator includes an asynchronous multi-threaded orchestrator:

• Worker Slider: Adjust parallel workers from 1 to 16 threads (default: 4).
• Throughput Optimization:
  • 1–2 Workers: Ideal for metered connections or servers with strict IP rate limits.
  • 4–8 Workers: Recommended for standard broadband and fiber connections migrating corporate domains.
  • 8–16 Workers: Recommended for high-bandwidth dedicated servers or cloud VMs handling large domain migrations.

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🏢 Protocol & Enterprise Cloud Authentication

MailMigrator supports both standard server credentials and enterprise tenant-wide modern authentication:

1. Standard IMAP / POP3 Servers

• Set the default Source and Destination server hosts and ports.
• Passwords for each mailbox are supplied via the accounts table or CSV import.

2. Microsoft 365 Enterprise Batch (Zero User Passwords)

• Select Microsoft 365 as the protocol.
• Enter your Tenant ID (Directory ID), Application (Client) ID, and Client Secret (see Modern OAuth2 Guide for Azure App Registration steps).
• MailMigrator automatically handles per-mailbox token generation dynamically. User passwords are not required!

3. Google Workspace Enterprise Batch (Service Account JSON)

• Select Google Workspace as the protocol.
• Click Browse and load your Google Cloud Service Account JSON key configured with Domain-Wide Delegation.
• MailMigrator signs JWT assertions and impersonates each target mailbox subject automatically without passwords.

4. Dynamic Column Adaptation (v1.5.2)

When Microsoft 365 or Google Workspace is selected:

• Username column headers automatically update to Source Mailbox (Email) or Dest Mailbox (Email).
• Password column headers update to Source Auth or Dest Auth displaying a clean 🔑 Admin OAuth2 badge.
• Password cell text editing is automatically disabled to eliminate operator confusion.

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📋 Adding & Managing Batch Accounts

The batch account table supports four flexible input methods:

1. Smart CSV Import (v1.5.2)

Click 📄 Import CSV to import any spreadsheet. The parser automatically detects headers and accommodates multiple enterprise formats:

• 2-Column Email Mapping: source@domain.com, dest@newdomain.com (ideal for enterprise tenant-to-tenant migrations without passwords).
• 1-Column Mailbox List: user@domain.com (ideal for exporting raw user lists directly from Google Admin or Microsoft 365 Admin centers).
• 4-Column Classic: SourceUser, SourcePassword, DestUser, DestPassword (for standard password-based IMAP/POP3 migrations).

2. Clipboard Paste (Excel & Tab-Separated)

Copy columns directly from Microsoft Excel, Google Sheets, or Notepad and click 📋 Paste Clipboard.

3. Loading Legacy ImapCopy.cfg

Click 📂 Load ImapCopy.cfg to load config files (a complete starter template is provided at Dist/ImapCopy.cfg). Server settings, concurrency, security flags, and all account pairs are automatically loaded into the table.

4. Direct Table Management

• ➕ Add Account: Inserts a new blank row into the DataGrid.
• ➖ Remove Selected: Deletes the currently highlighted row.
• 🗑 Quick Row Delete: 1-click red trash button on each row.
• Keyboard Delete: Highlight any row and press the Delete key.
• Inline Editing: Double-click any cell to modify email addresses or passwords.

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🔍 Pre-Flight Verification & Quotas

Before executing a large migration:

1. 🔍 Test All Credentials: Verifies connections and logins in parallel. Rows turn green (Ready) or red (Auth Failed).
2. 📊 Check Quotas: Interrogates source and destination storage limits in parallel (RFC 2087 IMAP QUOTA & POP3 sizing). Rows display health badges:
   • 🟢 Normal (< 80%)
   • 🟡 Warning (80% – 94%)
   • 🟠 Critical (95% – 99%)
   • 🔴 Exceeded (≥ 100%)
   • 🔵 Unlimited (Unmetered storage)
3. Pre-Flight Capacity Guard: If any destination mailbox lacks enough free capacity to receive the source mailbox contents, an alert warning is presented before transfer begins.

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▶ Executing the Batch & Interactive Controls

1. Click ▶ Start Batch Migration.
2. Per-Account Pause & Resume:
   • Need to inspect or adjust a specific account mid-migration? Click the ⏸ Pause button on that row.
   • Pausing an account immediately cancels its active network transfer and releases its worker slot so other queued accounts can proceed.
   • Click ▶ Resume at any time to re-queue the account into the active batch without resetting overall progress.
3. Batch Re-Run (v1.4.0):
   • If you need to perform a delta catch-up sync after DNS cutover, simply click ▶ Start Batch Migration again.
   • All account progress bars, speeds, and counters automatically reset cleanly, and the deduplication engine skips previously transferred messages in seconds.
4. Native Sleep Prevention:
   • MailMigrator automatically prevents the computer from sleeping during active batch migrations, ensuring unattended overnight transfers complete reliably.