How to Migrate Your Business Email Without Losing a Single Message
What Email Migration Actually Means
Email migration is copying every message, folder, and label from one IMAP server to another. When done right, the result is a 1:1 mirror—your new mailbox looks exactly like your old one, with every folder structure and message intact. This includes all attachments — every file attached to an email transfers with it.
This is not about forwarding future mail to a new address. It is about moving your entire email history so nothing gets left behind.
Important: Email migration transfers email data only — messages, folders, and attachments. Files stored in Google Drive, OneDrive, Docs, Sheets, or any other cloud storage are not part of your mailbox and will not be transferred. If you need those files, export them separately from the original provider before canceling your account.
Before You Start: What You Need
Gather these details for both your old (source) and new (destination) email accounts:
- IMAP server hostname — e.g.
imap.gmail.com,outlook.office365.com,mail.yourdomain.com - IMAP port — usually 993 (SSL) or 143 (STARTTLS)
- Full email address — e.g.
you@yourdomain.com - Password — for Gmail/Google Workspace, you need an App Password (not your regular login). For Microsoft 365, you may need an app password if 2FA is enabled.
If you are migrating to Mailbux, the destination server is my.mailbux.com on port 993. Use the email address and password you set up in your Mailbux dashboard.
Common IMAP Server Settings
| Provider | IMAP Server | Port | Notes |
|---|---|---|---|
| Gmail / Google Workspace | 993 | Requires App Password if 2FA enabled | |
| Microsoft 365 / Outlook | 993 | App password needed with 2FA | |
| Yahoo Mail | 993 | Generate app password in account settings | |
| Zoho Mail | 993 | Enable IMAP in Zoho settings first | |
| GoDaddy / Workspace | 993 | — | |
| Namecheap / Private Email | 993 | — | |
| Hostinger | 993 | — | |
| cPanel / Generic Hosting | 993 | Check your hosting panel for exact hostname | |
| Mailbux | 993 | — |
Migration Tools
Mailbux Migration Tool
Free online tool powered by imapsync. Works between any two IMAP providers — no Mailbux account needed.
- Up to 100 GB per mailbox
- Any provider to any provider
- Up to 3 parallel migrations
- Real-time progress tracking
- Cancel anytime
imapsync Online
The original imapsync web interface by its creator. Same IMAP-to-IMAP copy engine.
- Up to 3 GB per mailbox
- Any provider to any provider
- Single migration at a time
Both tools copy every IMAP folder and every message 1:1, preserving read/unread flags, folder hierarchy, and all attachments. Enter source and destination IMAP credentials, hit start, and watch the progress.
Step-by-Step: Full Migration Walkthrough
Here is the complete process from start to finish, whether you are moving to Mailbux or any other provider:
1. Set Up Your New Email Account (if needed)
Make sure the destination account exists and you can log in. If you are switching providers, create the mailbox on the new server first. If you are moving to Mailbux, create your free account, add your domain, and set up the email address that will receive the migrated mail.
2. Run the Migration
Use the migration tool to copy all existing messages. This does not affect your old mailbox — it only reads from the source and writes to the destination. Your old email keeps working normally during the transfer.
3. Verify the Copy
Log into your new mailbox and check:
- All folders are present (Inbox, Sent, Drafts, custom folders)
- Message counts match roughly — some providers exclude trash/spam from sync, which is normal
- Recent and old messages are both accessible
4. Update Your DNS (MX Records)
This is the step that switches live mail delivery to the new server. Update your domain's MX records at your domain registrar to point to the new provider. For Mailbux, the onboarding wizard gives you the exact records to set.
DNS propagation takes 1–48 hours. During this window, some mail may arrive at the old server and some at the new one. That is why you should keep the old account active until propagation completes.
5. Run the Migration Again (Catch Stragglers)
After DNS has fully propagated (wait 24–48 hours), run the migration tool one more time. This picks up any messages that arrived at the old server during the DNS switchover. Since imapsync only copies new messages, this second pass is fast.
6. Set Up Your Email Client
Configure your email client to connect to the new server, or use webmail to access your inbox right away. If you are migrating to Mailbux, you can download our desktop and mobile apps or access webmail directly from mailbux.com — all the links and setup instructions are there.
7. Decommission the Old Account
Once you have confirmed everything is working on the new provider for at least a week, you can cancel the old email service. Do not rush this step.
Migrating Multiple Mailboxes
If your company has 10 or 50 or 100 mailboxes to migrate, you do not need to do them one at a time. The migration tool supports up to 3 parallel migrations per session. Run a batch, wait for them to finish, run the next batch.
For very large migrations (hundreds of accounts), contact our support team and we can help coordinate the process.
Common Migration Issues and Fixes
| Problem | Cause | Fix |
|---|---|---|
| Authentication failed (source) | Wrong password or 2FA blocking IMAP | Generate an App Password (Gmail, Outlook, Yahoo all require this when 2FA is on) |
| Authentication failed (destination) | Account not yet created or wrong password | Log into the destination webmail first to confirm credentials work |
| Connection timeout | Firewall or wrong port | Make sure you are using port 993 with SSL. Check that IMAP is enabled on the source account. |
| Missing folders | Provider hides some IMAP folders by default | In Gmail, go to Settings → Labels and make sure folders are set to "Show in IMAP" |
| Slow transfer | Large mailbox with many attachments | This is normal. A 10 GB mailbox can take 1–2 hours. Let it run. |
Why Migrate to Mailbux?
- Unlimited email accounts at a flat rate — no per-user fees
- Free migration tool — move your entire team without paying for a third-party service
- Automatic DNS setup — SPF, DKIM, and DMARC configured through the onboarding wizard
- Keep your domain — use your existing yourname@yourdomain.com addresses
- No lock-in — standard IMAP means you can migrate away just as easily
Ready to Migrate?
Start with our free migration tool — no account needed:
Or create a free Mailbux account first, set up your domain and email accounts, then migrate your messages over.