Switching from Microsoft 365 or Outlook to Tobava Mail: the complete migration guide

Microsoft 365 migrations have one extra wrinkle Gmail doesn't: your business domain is usually pointed at Exchange, so the cutover has to be planned rather than clicked. Here's how to do it without a gap in delivery.

Two different migrations

Which path you follow depends on what you have:

• A personal Outlook.com / Hotmail / Live account — export your mail to .mbox files, import them, forward the old address, done.
• Microsoft 365 with your own domain — your domain's MX records point at Microsoft. The mailbox import is the easy half; the MX cutover is the part to plan.

Getting your mail out of Microsoft

Microsoft has switched off password sign-in over IMAP — for Microsoft 365 business mailboxes in 2022 and for personal Outlook.com accounts in 2024 — and app passwords no longer get around it. So instead of pointing an importer at outlook.office365.com, you export your mail to standard .mbox files and upload those. The free Thunderbird mail app handles Microsoft's modern sign-in, so it does the heavy lifting:

1. Install Thunderbird and add your Outlook / Microsoft 365 account. It opens Microsoft's own sign-in page, including your two-step verification.
2. Let it finish downloading your mail (right-click each folder → Properties → Repair Folder if a folder looks incomplete).
3. Install the ImportExportTools NG add-on, right-click a folder and choose Export folder → mbox. Repeat for the folders you want to keep.
4. In Tobava Mail, open Settings → Migration → Outlook.com / Office 365 (or Upload MBOX file) and upload each file. Up to 500 MB per file; split larger folders by year.

Already have a PST export from Outlook for Windows? Open it in Outlook, then let Thunderbird import from Outlook (Tools → Import → Import from another program → Outlook) and export to .mbox the same way.

Personal Outlook.com accounts

Export and import as above, then set up forwarding in Outlook.com under Settings → Mail → Forwarding so nothing sent to the old address is missed, and work through your important accounts as described in our Gmail migration guide.

Microsoft 365 with a business domain

Step 1: Inventory before you touch anything

List every mailbox, shared mailbox, distribution list and alias in the tenant. Microsoft 365 Admin Center → Users → Active users and Teams & groups → Shared mailboxes. Shared mailboxes are the ones most often forgotten — they hold years of accounts@, info@ and support@ history.

Step 2: Create the matching accounts in Tobava Mail

Add your domain in Tobava Mail first, then create one account per mailbox using the same local part (sarah@, accounts@, and so on). Matching addresses exactly means nothing in the import has to be re-mapped later. Note that role addresses such as accounts@ need their own account today — there is no shared-mailbox delegation, so plan who holds each one.

Step 3: Export and import each mailbox

For each mailbox — shared mailboxes included — export to .mbox and upload it into the matching Tobava Mail account, as described in Getting your mail out of Microsoft above. For many mailboxes, an admin can instead run a Microsoft Purview content search export to PST and convert those.

Step 4: Lower your DNS TTL — 48 hours ahead

This is the step that makes a cutover clean. In your DNS provider, drop the TTL on your MX records to 300 seconds at least 48 hours before the switch. Resolvers worldwide will then pick up the new records within minutes instead of hours.

Step 5: Cut over MX, SPF, DKIM and DMARC together

On cutover day, update all four in one sitting:

• MX → Tobava Mail's mail exchangers (shown in your admin panel)
• SPF → replace Microsoft's include:spf.protection.outlook.com with Tobava's include; don't leave both unless you're deliberately running split delivery
• DKIM → publish the DKIM TXT record exactly as shown in your Tobava Mail domain settings, using the selector given there
• DMARC → keep your existing policy, but start at p=none for a week if you've never had one, then tighten

If any of those four are new to you, our SPF, DKIM and DMARC explainer breaks down what each one actually does.

Step 6: Keep the old tenant alive for 30 days

Don't cancel the Microsoft subscription the day you cut over. Keep it running for a month so that:

• Anything delivered to Exchange during DNS propagation is still retrievable
• You can export and import once more to catch messages that arrived mid-migration — messages already imported are skipped automatically
• A rollback is still one DNS change away if something unexpected surfaces

Step 7: Verify before you call it done

Send test mail in both directions, and check a received message's headers show spf=pass, dkim=pass and dmarc=pass. Gmail's Show original view is the fastest way to read this.

What about Teams, SharePoint and OneDrive?

Tobava Mail includes an equivalent set in the same account: Docs, Sheets and Slides for documents, encrypted Drive for file storage, Meet for video calls, plus Calendar and Chat. Export SharePoint/OneDrive content as normal files and upload to Drive — no proprietary format lock-in on our side.