- An organizer has a Microsoft Exchange Server 2016, Exchange Server 2013, Exchange Server 2010, or Exchange Server 2007 mailbox.
- Attendee mailbox is in another Exchange organization that uses Exchange Server 2016 or Exchange Server 2013 as the Autodiscover endpoint.
- Availability address space is used for cross-forest free/busy data.
- The Autodiscover service uses the DNS method.
Note This issue may occur on any Exchange clients, such as Microsoft Outlook, Outlook Web App, an Exchange Web Services (EWS) application, or any other client that tries to retrieve free/busy information.
However, the Exchange Server 2013 Client Access server in the attendee forest cannot locate a mailbox for this email address and responds with a 404 status.
$m = Get-Mailbox <alias>Note Replace "<alias>" in the command by using the alias of the mailbox in your organization. Replace the domain "domain.com" with the domain that is found in the HttpProxy log.
$m.EmailAddresses += "smtp:01B62C6D-4324-448f-9884-5FEC6D18A7E2@domain.com"Set-Mailbox $m -EmailAddresses $m.EmailAddresses