Create the destination users, check their capacity and obtain authorised source access. Confirm the source's secure IMAP hostname, port, certificate and connection limits. Keep the old service active during the copy and final mail-routing transition.

1. In Zoho Mail Admin Console, open Data Migration and start or create a migration.
2. Add the source server with IMAP selected. Prefer the source provider's TLS-protected connection, normally port 993, and keep certificate verification enabled.
3. Choose folders and date scope. Set a cautious connection limit that the source permits.
4. Under the migration's Users tab, map a pilot source mailbox to the correct existing destination account. Use the supplied CSV format only when a bulk import is appropriate.
5. Start the migration and inspect the user's progress and Mail Failures. Correct authentication or capacity errors before expanding to the remaining accounts.

Compare representative old and recent messages, Sent items, nested folders and attachments. Raw message counts can differ when providers handle special folders differently, so sample actual business records as well.

After the planned routing change, perform a final incremental copy using the retry or synchronisation option available to your organisation. Zoho's Sync availability can depend on rollout. Verify the offered behaviour before relying on it for the cutover.

Suppose the source mailbox contains Projects, subfolders beneath Projects, and Sent. After confirming the exact names on that source server, choose Specific folders and use this illustrative Include Folder List:

"Projects", "Projects/*", "Sent"

The explicit Projects entry selects the parent folder, while Projects/* includes its subfolders. Replace Sent with the source server's actual sent-mail folder name. Pilot one source user mapped to the intended existing Zoho account. Check a message directly in Projects, one in a nested project folder and one sent message after the copy. Confirm that an unrelated folder was outside the selected scope. Keep credentials unchanged for the active migration and inspect Mail Failures before expanding the job.

If authentication fails, check source access rules and whether a temporary app credential or provider-specific migration method is required. Do not bypass certificate errors as a routine fix. If the migration pauses for storage, resolve destination capacity before resuming. Keep credentials and any migration CSV in restricted storage, then remove temporary access after acceptance.

• Moving business email without losing track of messages
• Adding a user to Zoho Mail with the correct policy and licence
• Managing mailbox storage and quota warnings in Zoho Mail
• Importing and cleaning contacts in Zoho Mail

• Zoho: IMAP Migration
• Zoho: Migrate To Zoho Workplace