Migrate from Microsoft 365 to OVH: What You Need to Know

More and more businesses leave Microsoft 365 to bring their email back to OVHcloud: European hosting, clearer euro billing and flat-rate mail plans. The good news is that mailboxes, calendars, contacts and files can be moved without losing a single message or interrupting delivery — provided you prepare the audit, keep both platforms live during the cutover and know the few pitfalls specific to Microsoft 365.

What gets migrated — and why people switch back

A business email migration is about far more than the messages. Several data types need to move, each with its own constraints:

• Emails: entire Exchange Online mailboxes, including folders and sub-folders, with original dates preserved.
• Contacts: personal address books and shared lists.
• Calendars: appointments, invitations and recurring events.
• Files: documents stored on OneDrive for Business and SharePoint sites.

On the OVHcloud side, you pick the target to suit your needs: MX Plan (bundled with the domain), Email Pro, Hosted Exchange or the Zimbra collaborative suite. People switch for European hosting, a predictable per-user cost and independence from a single ecosystem. Whatever the reason, the goal is the same: everyone finds their complete history on Monday morning, having lost nothing.

Step 1 · Audit what you have before touching anything

A successful migration starts with a precise inventory:

• the number of mailboxes to migrate and their size (a 50 GB mailbox does not move in the same window as a 2 GB one);
• shared mailboxes, distribution lists and aliases;
• the domain and its registrar, the current DNS/MX records and above all their TTL — lower it to 300 seconds a few days before cutover to speed up propagation;
• OneDrive/SharePoint files and their sharing permissions.

The larger the volume, the earlier you should start and the longer you let the sync run in the background.

Step 2 · Provision OVHcloud

Order the right email plan in the OVHcloud Control Panel, then attach your domain and recreate the user accounts — ideally with the same addresses as in Microsoft 365 so nothing changes for correspondents. Also create the aliases, groups and shared mailboxes. Do not change the MX records yet: at this stage, mail still lands on Microsoft 365.

Step 3 · Migrate the email

Moving the email relies on an IMAP sync: you connect the Microsoft 365 source to the OVH mailbox and copy the folders while preserving their structure. OVHcloud provides an IMAP import assistant in its Control Panel that can pull the contents of an external account.

Watch out for one major pitfall: Microsoft has disabled Basic Authentication for IMAP on Exchange Online. A plain password-based IMAP import will therefore often fail. Two reliable options: use a migration tool that supports OAuth2 / modern authentication, or export each mailbox to PST from Outlook (File → Open & Export → Import/Export) and then re-inject the folders into the OVH mailbox through an Outlook profile connected over IMAP. Either way, run an initial sync followed by a delta pass to catch messages that arrived in the meantime — no downtime window is imposed on users.

Step 4 · Contacts, calendars and files

IMAP only carries mail. Export your contacts as vCard/CSV and your calendars as ICS from Microsoft 365, then import them into the OVH webmail (or into Hosted Exchange/Zimbra depending on the plan). For files, download the folders from OneDrive and the SharePoint libraries, then move them to your new OVH storage space, a network share or a company NAS. Always re-check permissions: a company-wide share on SharePoint does not carry over automatically.

The secret to a zero-downtime cutover: never turn off the source until the destination is verified. Both mailboxes coexist for a few days while mail finds its new route.

Step 5 · Switch DNS/MX without downtime

Once the initial sync is done, change the domain's MX records to point to the ones OVH provides (for example mx*.mail.ovh.net for MX Plan, or the values specific to Email Pro / Hosted Exchange). Add the autodiscover CNAME, the SPF record, the DKIM key generated by OVH and a DMARC policy to protect deliverability. Thanks to the TTL you lowered in Step 1, propagation usually takes a few dozen minutes; keep Microsoft 365 active for another day or two while the last messages find the right destination.

Step 6 · Verify and reconfigure clients

After cutover, confirm that a test email lands in the OVH mailbox and that calendars are complete. Then reconfigure clients: in Outlook, remove the old Exchange Online account and add the OVH account (IMAP/SMTP for Email Pro, an Exchange profile for Hosted Exchange). On mobile, replace the Microsoft 365 account with the new one. Remember to update signatures, filters and calendar shares.

Common pitfalls

• Basic Auth disabled: on Exchange Online, plan for an OAuth2 tool or a PST export — password-only IMAP is no longer enough.
• Rate limits: Microsoft enforces access quotas; a very large mailbox can take several hours — plan generously.
• Duplicates: re-running a full migration instead of a delta duplicates messages. Stay in incremental mode.
• Recurring calendars: complex series or badly set time zones can shift — check them first.
• Sharing permissions: OneDrive/SharePoint rights do not map one-to-one; re-verify sensitive access.

How much it costs: Yuna7 vs an IT contractor

Having a contractor migrate Microsoft 365 to OVHcloud often costs several hundred dollars, with quotes and lead times. Yuna7 automates the cutover and you only pay for what you actually use — you can even try it for free.

Let Yuna7 migrate Microsoft 365 to OVHcloud for you

Describe your migration in one sentence: Yuna7 audits your mailboxes and domain, provisions the OVH plan, handles the email export/import (working around the Basic Auth shutdown), moves contacts, calendars and files, switches the DNS/MX records at the right moment and verifies everything arrived — you simply approve the sensitive steps. Far cheaper than a technician, and launched in minutes.