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Zero-Downtime Email Migration: The Parallel Delivery Strategy

Switching email providers often causes anxiety about missing important messages during the transition. Whether you are moving from Google Workspace, Microsoft 365, or another hosting provider, potential data loss is a major concern.

At Gozen Host, we use a Parallel Delivery strategy to guarantee that no email gets lost in the void during your DNS switch. By keeping both your old and new inboxes active for a short overlap period, you catch every single message.

The Concept: Parallel Delivery

Before you start, understand how Parallel Delivery works using the "72-Hour Golden Rule."

graph LR
    A[Sender] --> B{DNS Propagation}
    B -->|Old Path| C[Old Provider: Gmail/Outlook]
    B -->|New Path| D[Gozen Host]
    C --> E[You Check Old Inbox]
    D --> F[You Check New Inbox]
    style B fill:#f9f,stroke:#333,stroke-width:2px
    style C fill:#ffe6cc,stroke:#d79b00,stroke-width:2px
    style D fill:#e6ffcc,stroke:#82b366,stroke-width:2px
    style E stroke-dasharray: 5 5
    style F stroke-dasharray: 5 5

The Golden Rule

Never cancel your old hosting or delete your old mailboxes until 72 hours AFTER you switch your DNS.

During the propagation period (up to 48-72 hours), the internet is "confused." Some emails will go to your old server, others to Gozen. You must keep both doors open to receive everything.

Phase 1: Pre-Migration Preparation

1. Lower your DNS TTL

Locate your current DNS provider (where your nameservers point) and find your MX Records. Lower the TTL (Time to Live) to 300 seconds (or 5 minutes).

  • Why? This tells the internet to check for updates every 5 minutes instead of every 24 hours, making your final switch almost instant.
  • Timing: Do this at least 24 hours before you plan to migrate.

2. Recreate Mailboxes on Gozen Host

Before moving data, the "buckets" must exist on our servers. Log in to your specific Control Panel and create the exact same email addresses (e.g., hello@domain.com).

Go to Emails > Add Email Account. Ensure the quota matches or exceeds your current usage. View Enhance Guide

Navigate to Email Accounts > Create. View cPanel Guide

Go to the Mail tab > Create Email Address.

Phase 2: Transferring Your Data

You have two primary ways to move your existing history (folders, sent items, etc.).

This is a server-to-server transfer. It is the fastest and most reliable method.

  1. Use a tool like imapsync or the migration wizard inside your Gozen control panel.
  2. You will need the IMAP Server Address of your old host (e.g., imap.gmail.com or outlook.office365.com).
  3. Enter the credentials for both the source (Old Host) and destination (Gozen Host).
  4. Click Sync. Your folders will begin appearing in Gozen Host webmail immediately.

Best for single accounts or small mailboxes.

  1. Add both your Old Email and New Gozen Email to a desktop client like Outlook or Apple Mail.
  2. Simply select the folders/emails in the old account.
  3. Drag and drop them into the folders of the new account.
  4. Wait for the "Syncing" status bar to finish before closing the application.

Phase 3: The "Cutover" (The Switch)

Once your data is synced, it’s time to tell the world to send new mail to Gozen Host.

1. Update your MX Records

Replace your old records with your Gozen Host mail server details.

Type Host/Alias Priority Value / Destination
MX @ 0 mail.yourdomain.com

2. Update SPF & DKIM

Ensure you update your SPF and DKIM records to include Gozen Host, otherwise your outgoing mail might land in spam. This is crucial for maintaining your domain reputation.

  • New SPF Value: v=spf1 include:_spf.gozenhost.com ~all

Learn more about SPF, DKIM, and DMARC

Phase 4: The 48-Hour Overlap

This is the most critical phase for achieving "Zero-Downtime."

  1. Monitor Both Inboxes: For the next 48 hours, check both your old (Google/Old Host) webmail and your new Gozen Host webmail.
  2. Final Delta Sync: After 48 hours, run one last "Sync" to catch any stray emails that landed on the old server during the propagation window.
  3. Decommission: Once 48 hours have passed and no new mail is arriving at the old server, you can safely cancel your old service.

Troubleshooting

I can't connect to Gmail via IMAP

If you are migrating from Google Workspace (G Suite), you must: 1. Enable IMAP Access in Gmail Settings (Forwarding and POP/IMAP). 2. Generate an App Password if you have 2-Factor Authentication (2FA) enabled. Google will not allow a direct login with your primary password for migration tools like IMAPSync or Outlook.

Missing Folders in Outlook or Apple Mail

If folders are missing after syncing, ensure your mail client is "Subscribed" to all IMAP folders. * Outlook: Right-click the Inbox > IMAP Folders > Query > Select all > Subscribe. * Webmail: Check the "Settings" > "Folders" menu to ensure all migrated folders are set to "Visible." * Apple Mail: Ensure "All Mail" or specific labels are checked in your Gmail settings before the sync.

Next Step: Need help with your specific MX records? Contact our Migration Team for a free review of your DNS setup.