Gmail iPhone synchronisation

Question

I use Gmail on my iPhone and New Outlook on my Windows PC, with a Microsoft 365 Family subscription.

After a recent Microsoft download/update, Gmail synchronisation stopped working correctly in Outlook.

● Both devices can send and receive emails.

● Reading an email in Outlook does not mark it as read on my iPhone.

● Deleting an email in Outlook removes it from Outlook but leaves it in Gmail.

● Recent emails appear in Outlook but cannot be found in Gmail.

● Gmail works correctly in Chrome and synchronises with my iPhone.

● I do not want to unlink or remove my Gmail account because Outlook contains emails that aren’t visible in Gmail.

Please investigate the New Outlook–Gmail synchronisation problem and help restore two-way synchronisation without losing any emails.

Answer 1

@adrian rayner said

I do not want to unlink or remove my Gmail account because Outlook contains emails that aren’t visible in Gmail.

I understand your concern. And removing the GMail account will probably result in any mail that only exist in Outlook being lost. A test please to confirm that some emails really only exist in Outlook. I am asking for this because that is an unusual situation.

Pick a specific message that appears in New Outlook but not in Gmail. Search Gmail Web for the exact subject line and also check GMail All Mail. Do you find it?

Gmail works correctly in Chrome and synchronises with my iPhone.

Do I understand correctly - You are using the GMail App on your phone? Not Outlook for iOS.

Answer 2

The symptoms point to a New Outlook and Gmail sync/state issue rather than a Gmail sign-in failure, because sending and receiving still works on both devices.

Use this check order to avoid losing mail:

1. First verify whether the Outlook-only messages actually exist in Gmail
   • Open Gmail on the web in Chrome.
   • Search for the subject of a message that appears in New Outlook but seems missing in Gmail.
   • Check Sent and All Mail.
   • If the message is in Sent or All Mail, the message was sent or stored in Gmail and the issue is Outlook sync/state.
2. Check Gmail IMAP settings and label visibility In Gmail on the web, go to:
   • Settings > See all settings > Forwarding and POP/IMAP
     • Confirm IMAP is enabled.
     • Confirm no folder size limits are configured.
   • Settings > Labels
     • Confirm the affected labels/folders have Show in IMAP enabled.
   This matters because IMAP and label mapping can affect whether read state, deletions, and folder contents appear consistently across Outlook and Gmail.
3. Test whether the problem is specific to New Outlook Add the same Gmail account to another mail client, such as classic Outlook. If folders and message state sync correctly there, the problem is specific to New Outlook rather than the Gmail account.
4. If the issue started after an update, refresh the Outlook sync state Since sending/receiving still works, a fresh sync can help:
   • Sign out of Outlook completely.
   • Clear the application’s local data.
   • Sign in again and add the Gmail account back if needed.
   This is the least destructive way to force a fresh synchronization state.
5. Do not remove the account until mail safety is checked Removing the account from Outlook does not delete mail from Gmail; messages stay on Google’s servers. In Outlook, cached mail and folders for that account are removed from the profile and return after the account is added again and sync completes. Important risk: if there are items stored in Outlook-only local folders, such as folders marked “This computer only”, export them before removing the account, otherwise they can be lost.
6. Understand the sync model in New Outlook New Outlook for Windows can sync Gmail accounts to the Microsoft Cloud. That sync supports mail features for Gmail and Yahoo, and provides cloud-based synchronization between the email provider and Microsoft data centers. If Gmail works correctly on the web and iPhone but not in New Outlook, the fault is likely in the New Outlook sync layer rather than in Gmail itself.
7. If calendar or contacts are part of the issue IMAP only syncs email. It does not sync calendar or contacts. For Outlook mobile scenarios, calendar and contacts depend on supported account types and sync methods.

A safe recovery path is:

• Verify missing mail in Gmail web using All Mail.
• Confirm IMAP enabled and Show in IMAP for affected labels.
• Test the same account in classic Outlook.
• Only after that, refresh New Outlook local state or remove/re-add the account, after exporting any This computer only items.

---

• New Outlook is not syncing with one of my Gmail accounts - Microsoft Q&A Problem
• When I reply to an email and send the message, it remains in draft (New Outlook for Windows) - Microsoft Q&A
• Not receiving Gmail in Outlook - Microsoft Q&A
• Sync your account in Outlook to the Microsoft Cloud
• Sync account in Outlook for Mac to Microsoft Cloud
• Can't sync calendar and contacts with my phone or tablet