Switch from Proton Mail to Microsoft 365 Business: step by step

How to move your mail, contacts and address from Proton Mail to Microsoft 365 Business without losing anything. Most moves take an evening to set up, then a few weeks of forwarding.

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1. Before you start

   • Check where your address lives. If it ends in @proton.me, it belongs to Proton Mail and stays there: you'll forward your mail and tell people your new address. If it's on your own domain, like you@yourname.co.uk, it comes with you: you'll change a few DNS settings.
   • Check the space you need. See how much mail you have in Proton Mail, and compare it with Microsoft 365 Business's plans (the cheapest is Business Basic, £5.40 per user a month, yearly, ex VAT, with 50 GB).
   • Read the small print. Microsoft 365 Business's page covers exporting, cancelling and refunds under "Before you sign up".

2. Open your Microsoft 365 Business account

   Sign up on Microsoft 365 Business's website (One month free on some plans), and turn on two-step sign-in straight away. You'll find the link on Microsoft 365 Business's page: Microsoft 365 Business.

3. Bring your mail across

   Export, then copy it in with a mail app. First save your mail as files: Free Proton Mail Export Tool for Windows, macOS and Linux saves every email as EML files, for any plan. Proton Mail's guide ↗

   Then open the files in a mail app connected to Microsoft 365 Business over IMAP (Thunderbird with its free ImportExportTools add-on), and drag them into Microsoft 365 Business's folders.

   Your old mail stays where it is while it's copied, so nothing is lost if you need to start again.

4. Move your contacts and calendar

   Export your contacts as a .vcf file and each calendar as an .ics file from Proton Mail, then import them into Microsoft 365 Business. Most providers have both options in their contacts and calendar settings.

5. Keep your @proton.me address working

   1. Forward new mail. Look in Proton Mail's settings for automatic forwarding, and add your new address.
   2. Tell people. Send your new address to the people who matter, and add it to your email signature.
   3. Update your sign-ins. Change the email address on your bank, shopping, social and work accounts. A password manager's list of saved sign-ins is the quickest checklist.
   4. Keep the old account open for a while. Mail will keep arriving there for months. Sign in now and then so it isn't closed for not being used.

6. If you use your own domain

   Your address moves with you. Do this after your mail has been copied:

   1. Add your domain in Microsoft 365 Business's settings, and create the same addresses there.
   2. A day before, lower the TTL on your domain's MX records (to 300 seconds, say), so the change takes effect quickly.
   3. Replace the MX records with Microsoft 365 Business's, and swap Proton Mail's entry in your SPF record for Microsoft 365 Business's.
   4. Add Microsoft 365 Business's DKIM record, and keep your DMARC record.
   5. Check the result with a free DNS checker before you rely on it.

   Not sure what these mean? See my email glossary.

7. Check everything arrived

   • Compare the number of emails in each folder on both sides.
   • Send a test email to your new address from another account, and reply to it.
   • Check that mail forwarded from Proton Mail is arriving, and isn't going to spam.

8. Close Proton Mail, when you're ready

   Wait at least a month, until nothing new arrives there. On a free account you can leave it open with forwarding on instead. Before you close a paid account, download a last copy of your mail.

   • Cancelling: Cancel in your account dashboard before the renewal date.
   • Refunds: Full refund if you cancel and ask within 30 days of your first purchase, once per person; not for cash or bank transfer payments.
   • Renewal: Renews automatically at the price at the time of renewal, which can differ from what you first paid.

   From Proton Mail's page: Proton Mail.

I checked the providers' help pages on 24 October 2026. Menus move, so if a step doesn't match what you see, tell me and I'll update it.

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