Fixing Zoho Mail Sync Issues with Microsoft Exchange

Zoho Mail Sync Issues with MS Exchange: Common Fixes

Zoho Mail connects to Microsoft Outlook and mobile devices using Exchange ActiveSync (EAS), letting you two-way sync email, calendar, contacts, tasks, and notes. When this sync misbehaves, the cause is usually one of a small number of known issues.

Repeated sign-in prompts or stuck sync in Outlook

This is often caused by a corrupted local Outlook cache (OST file). To rebuild it:

  1. Close Outlook.
  2. Go to Control Panel, then Mail (32-bit), then Email Accounts.
  3. Select your Zoho account, click Change, untick Use Cached Exchange Mode, click Next, then Finish.
  4. Restart Outlook and let it sync in online mode.
  5. Re-enable Cached Mode afterwards if you want it, which rebuilds a fresh OST file.

"Invalid credentials" on mobile sync

If your Zoho account has two-factor authentication enabled, mobile EAS sync requires an application-specific password rather than your normal account password. If mobile sync suddenly stops with an invalid credentials error while other access methods like IMAP keep working, generate a fresh application-specific password from your Zoho Mail account's Two-Factor Authentication settings and use that for the EAS setup.

Correct server settings

For business domain accounts, the incoming server for Exchange ActiveSync is msync.zoho.com, with your full email address as the username.

Note: Exchange ActiveSync is supported for business paid plans only, not personal Zoho Mail accounts. Enable it under Settings, General, Active Sync, in your Zoho Mail account first.
Need help? 1 Cloud Consultants can help you diagnose and fix persistent Zoho Mail Exchange sync issues across your team's devices. Book a discovery call with 1 Cloud Consultants.