Email Migration for Companies: A Zero-Downtime Transition Guide

Whether due to high costs, inadequate technical support, or storage problems, many companies eventually decide to change their business email infrastructure. But at this point, IT managers and business owners are often gripped by a familiar fear: “Will my old emails be lost?”, “Will customer emails fall into the void during the switch?”

The email migration process can look intimidating, but with proper planning it can be completed with 100% zero downtime and no loss of data or business. Here is the step-by-step email migration guide.

1. Preparation and Inventory

The first step of moving from the old (source) server to the new (target) server is taking a complete inventory:

• Which accounts will be migrated? (Ahmet, Mehmet, info, accounting, etc.)
• Are there any forwards (alias accounts)? (e.g., emails sent to sales@ being routed to ali@)
• Do old emails (including folders) need to be transferred, or will this be a fresh start?

In particular, the capacity and data size of every account on your old provider must be measured.

2. Creating Accounts on the New Server

Before any DNS (domain name routing) changes are made, your business account must be activated on the destination email provider and all email accounts must be created.

Empty mailboxes with passwords set and configurations completed are opened on the target platform (e.g., Ulakmail). Distribution groups and alias addresses are also defined in the system at this stage.

3. Migrating Existing Data (IMAP Synchronization)

After accounts are created, the next step is copying your existing mail (Inbox, Sent, custom folders) to the new system. This is typically done server-to-server in the background using IMAP Migration tools.

During this process your old emails are not deleted from the source server; they are merely copied to the new server. Your employees can keep sending and receiving email through the existing system without noticing any disruption. Depending on data volume, transferring historical data can take from a few hours to a few days.

4. DNS Routing (MX Change)

Once all archived data has been successfully transferred to the new mailboxes, the critical step arrives: the DNS update.

The MX records that determine which email server your domain uses are switched to your new provider’s information. DNS caches around the world typically take 1 to 24 hours to see this change (propagation).

What happens at this stage? As DNS updates propagate, newly sent mail starts gradually arriving at your new server (your new mailbox). Email originating from places where the update hasn’t yet propagated will continue to land at your old server for a short while. No emails are lost or stuck in transit.

5. Final Sync (Delta Sync) and Device Updates

After DNS routing is complete (and you’ve confirmed that no new mail is arriving at the old server), a “Final Sync (Delta Sync)” is performed to capture the last few days’ worth of mail that accumulated on the old server during the MX change. This way, the two mailboxes are perfectly aligned.

At the same time, employees update the account settings (IMAP/SMTP) in Outlook, Apple Mail, or their mobile devices to point to the new server. From this moment on, all traffic flows entirely through the new platform.

Why Is Professional Support Important?

Faulty DNS configurations during an email migration (missing SPF and DKIM records, etc.) can cause your sent emails to land in spam or bounce back. Email migrations are sensitive operations and should be planned by professionals.

Ulakmail manages the entire migration process for its customers free of charge and with zero downtime, offering a “zero data loss” guarantee. To learn more about our migration process, feel free to get in touch.