This article describes possible causes for issues with Outlook 2016/2019 when connecting to an Exchange mailbox and ways to solve them.

Possible reasons for Outlook 2016/2019 issues with connecting to Exchange are:

There is no Autodiscover record created for your Domain

Outlook 2016/2019 can be set up to connect to Exchange only if there is a valid Autodiscover information for your domain. A special DNS record has to be configured for your domain.

To resolve the issue:

  • Contact a DNS hosting provider for your domain and create a CNAME record for the autodiscover hostname. Read the Knowledge Base article on What Is An Autodiscover Record And Why Do I Need It? for more information.
  • As a temporary solution (quick fix) you can modify the HOSTS file on the workstation adding a line for the autodiscover service location. Read the Knowledge Base article on How Do I Find And Modify Entries In The HOSTS File? for instructions on locating and updating the HOSTS file. You would need to add the following line:

Important: to protect your account information we cannot publish your Server names and DNS records in public Knowledge Base.To find out IP_for_AutdDiscover_service for your account navigate to HostPilotĀ® Control Panel > Home > Exchange servers and settings > Autodiscover. You would need to ping the hostname you find there from the Windows command prompt to get the IP.

Improper Autodiscover resolution

In case the Autodiscover record is properly configured via your DNS hosting provider, there can be a problem with the resolution of the record when Outlook fails to find the server Autodiscover points to. Outlook takes a series of steps before it finds the Autodiscover server and if it succeeds to find any information on any of the steps prior to resolving the DNS records for the automatic configuration will fail. Below are the steps Outlook performs when it tries to find the Autodiscover server:

  1. Check for M365 as a priority (only applies to Outlook 2016 version 16.0.6741.2017 and later versions)

    Outlook uses a set of methods to determine whether the provided user account comes from Microsoft 365.
    If Outlook falsely determines that you are an M365 user, an attempt is made to retrieve the Autodiscover from the known M365 endpoints. A user might experience various issues described in our Knowledge Base article How To Fix The Credential Prompt Error In Outlook For Microsoft 365 And Office Apps Users.
  2. SCP lookup

    Outlook gets information from Active Directory (on-premises Exchange server). If the record cannot be obtained from the local domain, the SCP lookup fails.

  3. HTTPS root domain query

    Outlook, which is not connected to a domain, uses the domain name part of SMTP address for this query:

  4. HTTPS Autodiscover domain query

    In case the HTTPS root domain query fails, the lookup of is performed.

    Note: if your website stores an XML file mentioned in step 2 or 3, the Autodiscover process will stop there. Contact your Web developer to remove the page from the site, so that the response of the links will be, for example, 404 Page not found.

  5. HTTP redirect method

    This step lets the Outlook find the Intermedia Autdiscover server. In case the correct DNS record is configured for your domain name, Outlook will successfully finish the autodiscover resolution process.

To make sure that Outlook skips all steps except for the HTTP redirect method create the following Registry values on the machines affected by the issue in the following manner:

Important: Back up the registry first and be careful when making any changes to it as any incorrect action may result in the OS crash.

  1. Open regedit: to do so, click the Start button and then in the Start Menu, either in the Run box or in the Search box, type regedit and press Enter.
  2. Navigate to HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\AutoDiscover
    Note: if AutoDiscover key could not be located under the mentioned location, you may add it manually.
  3. Create these DWORD values to exclude all checks before ExcludeHttpRedirect which is used by Intermedia:
PreferLocalXML 0
ExcludeHttpRedirect 0
ExcludeHttpsAutodiscoverDomain 1
ExcludeHttpsRootDomain 1
ExcludeScpLookup 1
ExcludeSrvRecord 1
ExcludeExplicitO365Endpoint 1

To perform the steps above automatically download and run the AutodiscoverFix.reg file.

  1. Reboot your machine to apply changes.