Outlook Not Syncing with a Gmail Account

When a Gmail or Google Workspace account stops updating in Outlook, the cause is almost always one of four things: Outlook is offline, the Google account needs to be re-authorized, IMAP settings or folder subscriptions are wrong, or the local data file is damaged. Work through the checks below in order. The early steps take seconds and resolve most cases.

Before you start

• Confirm the problem is Outlook and not Gmail itself. Sign in at mail.google.com in a browser. If a message is missing there too, it was never delivered and this article does not apply.
• Note whether the account is personal Gmail or a Google Workspace account managed by your organization. Workspace accounts may have administrator policies that block IMAP or third-party clients.
• Note the exact symptom: nothing sends, nothing arrives, only some folders update, or Outlook prompts repeatedly for a password. The symptom narrows down which section matters.

1. Check that Outlook is online and connected

1. Look at the status bar at the bottom of the Outlook window. It should read Connected. If it reads Working Offline or Disconnected, Outlook is not talking to Google.
2. Go to the Send / Receive tab and check the Work Offline button. If it is highlighted, click it once to turn offline mode off.
3. Press F9 (or click Send/Receive All Folders) and watch the status bar for a sync progress message.
4. If the status stays Disconnected, test general internet access in a browser. On a corporate network, a firewall or content filter may be blocking the Gmail IMAP and SMTP ports. Those are 993 for incoming (IMAP over SSL) and 465 or 587 for outgoing (SMTP).

2. Restart Outlook cleanly

Outlook can leave a sync thread stuck after a sleep or network change. Close Outlook, wait ten seconds, and reopen it. If it will not close, open Task Manager, end the OUTLOOK.EXE process, then reopen Outlook.

3. Re-authorize the Google account

Google access tokens expire when a password changes, when two-step verification is enabled or reset, when an administrator revokes sessions, or when the account is flagged for unusual activity. The usual symptom is a repeating password prompt or a silent failure to download new mail.

1. In Outlook, go to File > Account Settings > Account Settings.
2. Select the Gmail account and click Repair. For accounts added with modern authentication, Outlook opens a Google sign-in window.
3. Sign in with the Gmail address and password, complete any two-step verification prompt, and click Allow on the permissions screen.
4. Restart Outlook and press F9.

If no Google sign-in window appears, or the window appears and immediately closes, the account was likely added using an older password-based method. Continue to the next section.

Accounts using an app password

Google no longer accepts a normal account password from mail clients. If the account was configured with basic authentication, it needs a 16-character app password generated in the Google account's security settings, and two-step verification must be enabled first.

• Generate the app password from the Google account security page under App passwords.
• In Outlook, go to File > Account Settings > Account Settings, select the account, click Change, and paste the app password into the password field with no spaces.
• If a previous app password was revoked, the old one will never work again. Generate a new one.

For Google Workspace accounts, an administrator may have disabled app passwords or blocked less secure sign-in entirely. In that case the account must be re-added using the modern authentication flow. Contact your administrator or open a ticket with ServerNova.

4. Confirm IMAP is turned on in Gmail

1. Sign in to Gmail in a browser.
2. Click the gear icon, then See all settings.
3. Open the Forwarding and POP/IMAP tab.
4. Under IMAP access, make sure Enable IMAP is selected.
5. Click Save Changes at the bottom of the page, then restart Outlook.

If the IMAP option is missing or grayed out on a Workspace account, your administrator has disabled it for the organization.

5. Check for a Google security block

Google sometimes blocks a client it does not recognize, particularly after travel, a new device, or a VPN change.

1. Check the Gmail inbox in a browser for a "Critical security alert" or "blocked sign-in attempt" message and confirm the activity was you.
2. Review recent security activity on the Google account page and approve the Outlook device if listed.
3. Retry the sync in Outlook.

6. Verify server settings

If the account was set up manually or imported from another machine, the server values may be wrong. Open File > Account Settings > Account Settings, select the account, click Change, then More Settings.

Setting	Value
Incoming server (IMAP)	imap.gmail.com
Incoming port	993, SSL/TLS
Outgoing server (SMTP)	smtp.gmail.com
Outgoing port	465 (SSL) or 587 (TLS)
Outgoing server authentication	Required, using the same credentials as incoming
User name	The full email address

Click Test Account Settings after any change.

7. Fix missing or stale folders

Gmail labels appear as IMAP folders in Outlook, but Outlook only downloads folders it is subscribed to. If mail is arriving in the inbox but a label folder is empty or absent, subscription is the likely cause.

1. In Outlook, right-click the Gmail account name in the folder list and choose IMAP Folders.
2. Click Query to list all available folders.
3. Select the folders you want and click Subscribe.
4. Click OK, then press F9.

You can also control which labels are exposed to IMAP from the Gmail web interface under Settings > Labels by checking Show in IMAP for each label.

Also check the Gmail setting Folder size limits on the Forwarding and POP/IMAP tab. If a limit is set low, Outlook will only see part of a large folder.

8. Check Send/Receive group settings

1. Go to Send / Receive > Send/Receive Groups > Define Send/Receive Groups.
2. Select the group containing the Gmail account and click Edit.
3. Confirm the account is checked and that Receive mail items and Send mail items are both enabled.
4. Back on the main dialog, confirm Schedule an automatic send/receive every [n] minutes is checked and set to a reasonable interval such as 5.
5. Click Close and press F9.

9. Clear a stuck outbound message

A single large or malformed message sitting in the Outbox will stall the entire send/receive cycle, which often looks like a total sync failure.

1. Open the Outbox folder.
2. Switch Outlook to offline mode (Send / Receive > Work Offline) so the message cannot start sending while you work.
3. Drag the stuck message to Drafts or delete it.
4. Turn off offline mode and press F9.

Gmail limits attachment size to 25 MB. Messages larger than that will fail repeatedly.

10. Rebuild the local data file

Outlook stores a local copy of the Gmail mailbox in an .ost file. If that file is damaged, sync stops even though the account and credentials are fine. Rebuilding is safe for IMAP accounts because all mail lives on Google's servers, but confirm nothing exists only locally before you proceed.

1. Close Outlook.
2. Open Control Panel > Mail > Data Files.
3. Select the Gmail account entry and click Open File Location.
4. Close the Mail dialogs, then rename the matching .ost file by adding .old to the end.
5. Reopen Outlook. It will create a fresh data file and redownload the mailbox. This can take a long time on a large mailbox.

Do not delete the renamed file until you have confirmed the rebuilt mailbox is complete. Local-only items such as drafts that never synced, or mail that was moved into a local folder, will not come back.

11. Create a new Outlook profile

If nothing above works, the profile itself may be corrupt.

1. Close Outlook and open Control Panel > Mail.
2. Click Show Profiles > Add, name the new profile, and click OK.
3. Add the Gmail account, completing the Google sign-in prompt when it appears.
4. Select Prompt for a profile to be used so you can switch back if needed, then start Outlook and pick the new profile.
5. Once the new profile syncs correctly, you can set it as the default and remove the old one.

Other things worth ruling out

• Add-ins. Start Outlook with outlook.exe /safe from the Run dialog. If sync works in safe mode, disable add-ins one at a time under File > Options > Add-ins.
• Antivirus email scanning. Mail-scanning modules in third-party security suites intercept IMAP and SMTP traffic and frequently break Gmail connections. Temporarily disable that specific feature to test.
• Pending updates. Apply Office updates via File > Office Account > Update Options > Update Now.
• Mailbox storage full. If the Google account is out of storage, new mail will not be delivered at all. Check the storage indicator in Gmail.
• Clock drift. A system clock more than a few minutes off can break the TLS handshake. Confirm the device is set to sync time automatically.

When to contact ServerNova

Open a ticket if any of the following apply:

• IMAP or app passwords are disabled by Google Workspace policy and you need an administrator change.
• The same failure affects multiple users in your organization, which points at a network, firewall, or policy issue rather than one workstation.
• A rebuilt profile still fails to authenticate.
• Mail appears to be missing rather than just not syncing.

Include the exact error text, the account's email address, the Outlook version from File > Office Account, and the steps you have already tried. Never send passwords or app passwords in a ticket.