To troubleshoot connectivity issues in Outlook, follow the steps listed below one by one and see if the problem persists after each step. 
Note: Outlook versions of 2003 and earlier are no longer supported. Windows versions older than Vista are not supported.

Important: Tests should be run while the user is experiencing connectivity issues.

The Outlook status bar might be showing Connected to Microsoft Exchange or Connected, but may not sync properly, or may show the Trying to connect... or Disconnected status.

  1. If the Outlook status is Working Offline, open the Send/Receive tab and disable Work Offline option.
  2. Check if you can log in to Webmail (OWA). If you cannot log in to OWA and get one of these messages:
    • Login or password incorrect. Verify your password is correct, ask account administrator to reset your password if necessary.
    • Server is unavailable. Clear the browser cache, try to login to OWA again. 
  3. Check the profile settings. Go to File (Tools) > Account Settings > double-click on Exchange email address > verify the Server address is correct > More Settings > Connection > Exchange Proxy Settings > verify the proxy address is correct.
    Important: to protect your account information we cannot publish your Server names in public Knowledge Base. You may find the correct server names in  HostPilotĀ® Control Panel > Home > Exchange servers and settings.

    If your server is Exchange 2013, the server name should be underlined and look like Such server name is expected behaviour for Exchange 2013 mailboxes.
    Connection tab is unavailable in Outlooks 2016 as they can only be configured via Autodiscover.
  4. Run Outlook in Online Mode: go to File (Tools) > Account Settings > double-click on Exchange email address > uncheck Use Cached Exchange Mode > save the changes > restart Outlook. Read the Knowledge Base article on How To Enable Cached Exchange Mode In Outlook for more information.
    If there is an improvement in Outlook performance in Online Mode, it means the Outlook local cache file (.OST) is corrupted.
    Note: You may need to reorganize your mailbox so that folders contain not more than 5000 items each as recommended in Outlook: Improving Performance.
  5. Run Outlook in Safe Mode: quit Outlook, navigate to Start > in Search field type in outlook.exe /safe (mind the space between .exe and /safe)> Enter.
    If the performance is better, disable the unnecessary Add-ins in Outlook. Read the Knowledge Base article on Body Of Messages Is Missing In My Outlook. What Do I Do? to find instructions on removing add-ins.
  6. Run trace route to your proxy server. You may find correct proxy server address in HostPilot > Home > Exchange servers and settings.
    Note: Despite the fact that normal websites may be opening fine, there can be some connection lags or interruptions on a particular network segment.

    If there are some asterisks (*) or the response time is > 200 ms within your network (first 2-3 hops), reboot your router or modem, and contact your ISP if necessary. If the asterisks appear beyond your Network, contact Support.
  7. Check Outlook Connection Status. Press CNTRL key and right-click the Outlook icon in the notification area > select Connection Status
    Connection status
    In the Exchange Server Connection Status window, you can view information about the current connections Outlook has established to the Exchange server. Provide Support with the screenshot of: SMTP Address, Display Name, Proxy Server ,Status and Avg Resp
    Connection status

If steps above did not help, provide Support with the results of the following tests:

  • Description of the issue(s).
  • Presence of issue(s) in OWA.
  • Differences in Outlook performance in Safe and Online modes.
  • Trace route results.
  • Test Email Autoconfiguration results.
  • Outlook and Windows versions.
  • Public IP address you are connecting from.
  • Client Access Server (CAS) you are connecting to. Browse the following link: https://your-proxy-address/server.aspx for Exchange 2007/2010, or https://your-proxy-address/scripts/server.aspx for Exchange 2013/2016.
    Important: to protect your account information we cannot publish your Server names in public Knowledge Base. You may find your proxy address in HostPilot > Home > Exchange servers and settings.

Note: You might need to take a screenshot. Read the Knowledge Base article on How Do I Create A Screenshot On Windows?

Outlook 2010/Exchange 2010:Reminders, Outbox, To-Do Bar, Outlook indexing issues

According to Microsoft, issues can occur when the msExchDelegateListLink attribute is set to the same mailbox (it is automapping itself).

It can cause issues with Outlook search - rebuilding index may work for a time, but the issue reoccurs. The Microsoft KB article indicates it can cause:

Reminders do not fire, e-mail stays in the Outbox, the To-Do Bar displays an error or Wndows Desktop Search frequently rebuilds the indexing of Outlook items

User may see the mailbox listed twice in Outlook. Also Outlook Test E-Mail Autoconfiguration tool > XML tab showed:

        <DisplayName>Yizhou Xie</DisplayName>

Microsoft KB article:

Fix is to remove the msExchDelegateListLink attribute.

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