At a glance
| From | Zoho Mail · imap.zoho.com:993 (SSL) |
|---|---|
| To | Microsoft 365 · outlook.office365.com:993 (SSL) |
| Copied | Every folder, read and flagged state, received dates. Duplicates are skipped. |
| Source mailbox | Opened read-only; nothing is changed or deleted. |
| Calendars and contacts | Not over IMAP: export and import .ics/.vcf |
Step by step
Prepare Zoho
Use your Zoho password, or an application-specific password if two-factor sign-in is on. EU accounts use imap.zoho.eu, India imap.zoho.in. Turn on IMAP access: Settings → Mail Accounts → IMAP → IMAP Access.
Prepare Microsoft 365
Create the users and assign licences with Exchange Online before you start. Enable IMAP on each mailbox (Exchange admin center → Manage email apps). Microsoft throttles IMAP uploads; 2 to 4 accounts in parallel usually runs fastest. Microsoft turned off password logins for IMAP, so use "Sign in with Microsoft" in the console. The mailbox must have IMAP enabled.
Enter the servers and accounts
In the console, use imap.zoho.com as the source and outlook.office365.com as the target (port 993, SSL). Add the accounts one per line (email, then password) or upload a CSV. To let each person type their own password, send invitation links instead.
Validate and estimate
"Validate accounts" tries every login; "Estimate size and time" shows the message count, total size and free space on the target.
Launch and watch
Start the migration and follow progress per account and folder with a live action log. Copied messages are never copied twice, and an interrupted run continues where it stopped.
Switch MX
After the first copy, point the MX record to the new provider and press "Final sync" to bring over mail that arrived in between.
Good to know about Zoho
- The folder "Newsletter" and "Notification" views are filters, not folders; the mail itself sits in Inbox and is copied from there.
Good to know about Microsoft 365
- Sent, Drafts, Trash and Junk are mapped to Sent Items, Drafts, Deleted Items and Junk Email automatically.
- Messages above the mailbox size limit (35 MB by default, up to 150 MB) are refused and listed as failed.
Questions
Will my email be deleted from Zoho?
No. The source is opened read-only; messages are copied and even their read state stays the same.
Are folders, read status and dates kept?
Yes. Every folder, the read and flagged state and the received date are copied as they are. Sent, Drafts, Trash and Junk are mapped to the target's own folders.
How long does it take?
Small mailboxes finish in minutes; a 5 GB mailbox usually takes one to three hours.
Can I move many mailboxes at once?
Yes. Add hundreds of mailboxes as a list or CSV and several run in parallel. If you do not want to collect passwords, send invitation links so each person types their own.
Are calendars and contacts moved too?
IMAP moves email only. Zoho or Microsoft 365 does not offer CalDAV/CardDAV, so export calendars and contacts as .ics/.vcf files and import them.
What does it cost?
You pay for days of access: pick a day, a week or a month and move unlimited accounts and messages in that time. There is a free trial for one small mailbox.
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Last updated: 18 September 2026