I have a domain on which two email services coexist at OVH:
A MXPlan service with 12 accounts, recently migrated to the new Zimbra webmail following the OVH migration campaign.
A Hosted Exchange service with 1 account.
Both services are configured in Non-authoritative mode on the domain, which allows their coexistence. Exchange is working well at the moment and I definitely do not want to break this configuration.
I would like to move certain addresses from my MXPlan to a Zimbra Pro offering.
My questions:
Should I order a separate Zimbra Pro service and then migrate the relevant accounts from MXPlan to this new service? Or is there a way to upgrade my current MXPlan (already on Zimbra webmail) directly to Zimbra Pro?
Does this operation require reconfiguring the domain’s MX or DNS records?
If so, how can I ensure that my Exchange service, currently functional on the same domain, will not be affected?
Can I migrate only certain addresses (not all 12) to Zimbra Pro, leaving the others on MXPlan?
Following my initial post — here’s what we’ve been able to clarify for those who come across this thread later:
Context: domain with MXPlan (migrated to Zimbra webmail) + Hosted Exchange already coexisting, and desire to add Zimbra Pro for certain addresses.
What we have confirmed:
Coexistence of multiple OVH email services on the same domain is possible, provided each service is set to non‑authoritative mode. The shared MX cluster (mx0-4.mail.ovh.net) then routes each mail to the correct backend based on the recipient address.
The authoritative/non‑authoritative mode is not fixed — confirmed by an OVH advisor in live chat: it can be changed afterwards if needed.
When ordering a new Zimbra service on a domain already in use, the configuration screen offers “Recommended configuration” (which switches the entire MX to this new service — to be avoided in a coexistence scenario) or “Custom configuration” (allows you to uncheck MX/SPF/SRV individually). The message “Your domain will be configured in authoritative mode” that appears on this screen seems generic and does not accurately reflect the actual configuration once MX/SPF are unchecked — also confirmed by support.
Watch out for the SRV record (autodiscover): if you keep Exchange, do not let Zimbra reconfigure the _autodiscover._tcp SRV — it would overwrite the existing Exchange configuration. A “SRV configuration error” diagnostic will appear on Zimbra in that case, but it is normal and harmless: it simply indicates that autodiscover remains dedicated to Exchange.
To migrate existing accounts (MXPlan) to Zimbra Pro, the official tool is OVHcloud Mail Migrator (omm.ovhcloud.com), compatible with Exchange/Zimbra/IMAP/POP. The procedure has two steps: migrate the content to a temporary account, then rename (delete the source account + assign the final address to the new account, with a 5‑minute gap between the two steps).
Technical support: my support tier did not allow opening a “consultation” ticket for this type of question (incidents only). The live chat (often via the AI assistant then escalated to a human) provided a clear answer.
To migrate an MXplan address to Zimbra Pro, you just need to add a licence to your existing Zimbra platform.
It is also possible to create a second Zimbra organisation if the address you want to migrate uses a domain name different from the one already in use on the platform, for example.
It is not possible to automatically migrate an MXplan offering to Zimbra (not yet :wink:)
There is no need to modify the DNS configuration in your case.
Yes!
For creating the address on Zimbra:
Once your licence is ready to be used on Zimbra, I invite you to rename your MXplan address – for example, change contact@domaine.fr to contact01@domaine.fr. This will allow you to recreate the address contact@domaine.fr on Zimbra.