The best email migration tool is the one that handles your exact source and destination, moves everything you need beyond mail, and lets you run a free pilot first. For a small IMAP move a command-line sync tool is enough; for Microsoft 365 or Google Workspace moves with files and Teams, use a hosted migration platform.
A bad email migration doesn't fail on the day. It fails a week later, when someone notices their sent items stopped in March, the shared mailbox didn't come across, or every message with three Gmail labels now exists three times. By then the old account's been cancelled. Almost every painful move traces back to choosing a tool for the mail and forgetting everything around it.
Where moves go wrong
- Moving only the mail. Contacts, calendars, shared mailboxes, aliases, rules and signatures are separate objects. Each tool's own page says which of these it moves. List what every user relies on, then hold each shortlisted tool to that list.
- Ignoring labels. imapsync's own Gmail FAQ explains that Gmail presents labels as IMAP folders, so a message with three labels lands in three folders after a sync unless you switch that off.
- Cutting over in one pass. Mail keeps arriving while you copy. Without a second, incremental pass (often called delta sync) after the switch, the gap between the first copy and the DNS change goes missing.
- Leaving DNS to the last minute. Microsoft's cutover guide warns that other mail servers remember where your mail lives until the record's TTL runs out, and suggests lowering it ahead of the switch to avoid delivery delays.
- Assuming passwords still work. Microsoft has removed basic password sign-in for IMAP in Exchange Online, and Gmail no longer lets third-party apps sign in with just a username and password. Your tool needs OAuth for both ends.
- Forgetting throttling. Microsoft says Exchange Online deliberately throttles mailbox moves when the service is busy. A move that looks like an afternoon on paper can stretch across days on a large tenant.
Who does the work: you, the vendor's cloud or the vendor's team
Self-run software. You install it, point it at the source and destination, and watch it. Desktop apps and command-line sync tools sit here. They're cheapest and suit small moves or technical admins, but you own every failure. If most of your mail is years old, consider moving recent mail and putting the rest into one of the email archiving tools instead.
Hosted platforms. The tool runs in the vendor's cloud, you configure projects in a browser and it works through mailboxes in batches. This is the normal choice for MSPs and for anything over a handful of users, because you can schedule passes, track progress per mailbox and rerun failures without babysitting a laptop.
Done for you. Some vendors offer a serviced option where their team plans and runs the move. You pay for the hours, and in return the risk and the 2am cutover belong to someone else.
The second fork is scope. Mailbox-only tools move mail, sometimes contacts and calendars. Suite tools also move files, chat and Teams, and whole Microsoft 365 tenants. If your move is part of a wider switch, such as a Google Workspace migration, mailbox-only is rarely enough.
Hosted platforms for business moves
MigrationWiz
A hosted platform MSPs reach for when a move covers mailboxes, documents, Teams or an entire Microsoft 365 tenant, not just inboxes.
CloudM Migrate
Plans and runs moves of users, mail and files into Google Workspace or Microsoft 365, and can be bought as a serviced migration.
Cloudiway
Licence-based migration for mail, archives, drives, Teams and Slack, sold as bundles that don't expire, for moves into M365 or Google Workspace.
AvePoint Fly
An enterprise service for organisations moving email, files, Teams and intranets together into Microsoft 365 or Google Workspace.
Transend Migration Console
Software with optional services from a small specialist, built to carry email and files between platforms without users losing access.
Desktop, command-line and provider tools
imapsync
A command-line IMAP sync tool for admins, copying every folder from one mailbox to another on Windows, Linux or Mac.
EdbMails
Desktop toolkit for Exchange, Office 365, PST, OST and MBOX data, handling recovery jobs as well as straight migrations.
Stellar Migrator for Exchange
Desktop software for Exchange and Microsoft 365 mailbox moves, with auto-mapping and delta sync and no PowerShell needed.
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Zoho Mail migration tools
If Zoho Mail is your destination, start with the provider's own set of tools for bringing over email, contacts and calendars.
Mailvita
A family of macOS desktop utilities for people moving, importing or exporting local mail on a Mac rather than a server.
Run a pilot before you commit
Three of the ten offer a free trial and one has a free route for small mailboxes, so there's no reason to buy blind. Here's a pilot you can run in about an hour:
- Create a test mailbox at the source and fill it with awkward content: a few thousand messages, a deep folder tree, a message with several labels or categories, a large attachment, a calendar invite and a handful of contacts.
- Create an empty mailbox at the destination with the same name. If your team shares an inbox such as sales@ or accounts@, add a small shared mailbox to the test as well, because it's a separate object from a user's own mail.
- Run the tool's first pass, then send five new messages to the source and run an incremental pass.
- Compare folder by folder. Message counts should match, the five late messages should be there, and nothing should be duplicated.
- Open the calendar invite and a contact at the destination, then check the shared mailbox arrived and that the people who need it can open it. Anything missing is a gap found before it cost you anything.
- Time the pass and multiply by your real mailbox sizes. That's your schedule, before throttling.
If the pilot passes, run it again on one real user who'll tell you honestly what's missing. Then batch the rest.
How the bill is worked out
Four of the ten publish a price on their own sites, and their starting figures run from about 100, a discounted figure on the day we read it, to the mid-400s, two quoted in euros and two in dollars. They aren't buying the same thing, though: one is a bundle licence that doesn't expire, one is a paid support package on top of a free tool, one is a single desktop software licence and one is a tier covering 25 mailboxes. So compare what each figure covers, not the number. The other six don't publish a price, which means asking for a quote.
For a small business the cheapest route is often a self-run tool plus your own time. For an MSP running dozens of moves, per-mailbox or bundle licensing with a hosted console pays for itself in hours saved. For a large tenant move with files and Teams, the cost is mostly in planning, and a serviced option is often worth it.
Do you make email migration tools? Tool makers can ask to be considered for a featured place on this list.
Match the tool to the move
- A few IMAP mailboxes between hosts: a command-line sync tool or the destination provider's own importer.
- Exchange on-premises to Microsoft 365: desktop migration software with delta sync, or a hosted platform if there are many users.
- Google Workspace to Microsoft 365, or the reverse, with files: a hosted suite tool that moves drives and chat as well as mail.
- An MSP doing this every month: a hosted platform with per-mailbox or bundle licensing and project tracking.
- Local mail on a Mac: a Mac desktop utility, since server tools can't see a local mail database.
- Moving providers altogether: pick the destination first with our email hosting comparison, then check whether it ships its own importer.
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Related: the moving page.
Frequently asked questions
What about aliases and forwarding addresses?
They usually live in the admin console, not inside the mailbox, so a mailbox copy may not bring them. Export the list of aliases, groups and forwarding rules from the old admin console and recreate them at the destination before you switch DNS.
When can we cancel the old account?
Not on cutover day. Keep it running until the final incremental pass has finished and users have confirmed their mail, contacts and calendars look right, plus a margin in case something turns up late.
What should staff be told before the switch?
The date, what they'll need to do on the day (usually signing in again on their phone and desktop mail app), and to avoid deleting or reorganising folders while the copy runs, since that's what makes counts stop matching.
