Zoho Mail to Microsoft 365 / Outlook Split Delivery Setup & Migration

I’m looking for an experienced Microsoft 365 / Exchange Online administrator to help set up a split email environment between Zoho Mail and Microsoft 365/Outlook for my business.

We currently have approximately 15 employee email accounts using Zoho Mail under our company domain. I do not want to migrate everyone to Microsoft at this time.

Initially, I want to move my account and potentially 1–3 other management accounts to Microsoft 365 / Outlook, while keeping the remaining employees on Zoho Mail.

The main reason for the move is Outlook/Exchange calendar functionality. We regularly receive Microsoft Outlook/Teams meeting invitations from government and other organizations, and I want the migrated users to have a proper Microsoft Exchange calendar where accepted meetings, availability, Teams invitations and reminders work normally.

Scope of work
Configure our company domain in Microsoft 365 without disrupting existing Zoho users.
Set up Microsoft 365 / Exchange Online mailboxes for the selected users.
Configure split delivery/coexistence between Zoho Mail and Microsoft 365.
Keep the majority of existing employees on Zoho Mail.
Start by migrating one test account first before moving any additional users.
Migrate the selected user's existing email and folders from Zoho to Microsoft 365.
Migrate or properly transfer existing calendar data and contacts where possible.
Preserve the user's existing @caregrowth.ca email address.
Ensure no historical email is lost during migration.
Configure Outlook desktop/web/mobile for the migrated account as needed.
Make sure Outlook Calendar works correctly for accepted meeting invitations.
Confirm Microsoft Teams meeting invitations integrate correctly with the Outlook calendar.
Configure and/or review necessary DNS/email authentication settings, including MX/routing, SPF, DKIM and DMARC.
Avoid negatively affecting mail delivery for employees who remain on Zoho.
Test all mail-flow scenarios before completion:
External sender → Microsoft user
External sender → Zoho user
Microsoft user → external recipient
Zoho user → external recipient
Zoho user → Microsoft user
Microsoft user → Zoho user
Confirm replies, aliases and existing email addresses function properly.
Verify there are no mail loops, duplicate messages or routing problems.
Very important — I also want training

I do not want to have to hire someone every time I add another manager to Microsoft 365.

Once the system is working, I would like you to show me how to add another existing Zoho user to Microsoft 365 in the future.

Ideally this would be done over screen share and/or with a short written procedure covering:

Creating the new Microsoft 365 user
Assigning the correct Microsoft license
Creating/configuring their Exchange mailbox
Migrating their Zoho mailbox
Updating whatever Zoho routing is required
Setting up Outlook
Confirming their calendar
Testing mail flow
Removing a Microsoft user or moving them back if ever required

The goal is for the initial infrastructure to be set up professionally, but for routine future additions to be something I can handle myself.

Current environment
Business domain: caregrowth.ca
Approximately 30 employees/mailboxes
Email currently hosted through Zoho Mail
Most employees will remain on Zoho
Approximately 1–4 management users will initially move to Microsoft 365
We want Microsoft 365/Exchange Online/Outlook for those users
Microsoft Teams may also be used by the management users
Requirements

Please apply only if you have experience with:

Microsoft 365 / Exchange Online administration
Zoho Mail administration
Zoho + Microsoft 365 split delivery/coexistence
DNS and MX records
SPF, DKIM and DMARC
IMAP/mailbox migrations
Outlook/Exchange calendar migrations
Troubleshooting cross-platform mail routing

Experience specifically setting up Zoho Mail and Microsoft 365 under the same business domain is strongly preferred.

Important safeguards

I want this completed with minimal or ideally no email downtime.

Please:

Do not migrate all existing Zoho users.
Do not delete existing Zoho mailboxes or historical email.
Do not cancel or disable Zoho.
Do not make destructive DNS changes without discussing them first.
Test using one Microsoft account before moving additional users.
Document important DNS and routing changes made during the project.
Confirm everything is working before the project is considered complete.

I will retain ownership/control of the Zoho account, Microsoft 365 tenant and domain registrar. Temporary administrative access can be provided as required.