Retrieving Free/Busy Status from Exchange Online Users: A Mysterious Case

As an organization, we have been facing a peculiar issue while trying to retrieve free/busy status of calendars of users in another organization, especially when their mailboxes are located in Exchange Online within the Exchange Hybrid setup. Despite our efforts to find reliable sources of information, we have been unsuccessful in resolving this problem. In this blog post, we will delve into the details of the issue and try to understand the reasons behind it.

Background Information

We are an organization A, and we have a collaboration with another organization B. Our collaboration involves sharing resources, data, and information between our calendars and mailboxes. To facilitate this collaboration, we have set up an Exchange Hybrid setup in Organization B, which allows us to access their mailboxes and calendars seamlessly. However, when we try to retrieve the free/busy status of users in Organization B, we encounter a strange issue.

The Problem

When the users in Organization B have their mailboxes located on-premise, we can easily retrieve their free/busy status from our organization A. However, when these users are migrated to Exchange Online within the Exchange Hybrid setup in Organization B, we as users from Organization A cannot retrieve their calendar free/busy status anymore. This is a strange and frustrating issue, as we have been unable to find any reliable source of information to answer our questions.

Questions and Inquiries

We have several questions and inquiries related to this issue, which are as follows:

1. Why does the free/busy status retrieval not work when an user in Organization A is retrieving it from an user in Organization B while the user’s mailbox of Organization B is located in Exchange Online within the Exchange Hybrid setup?

2. Is there any specific configuration or setting that needs to be done to enable free/busy status retrieval between organizations A and B?

3. Is there any known issue or limitation with Exchange Hybrid setup that prevents free/busy status retrieval between organizations A and B?

4. Are there any workarounds or solutions available to resolve this issue?

Conclusion

We hope that this blog post will help us find some answers to our questions and inquiries related to the strange issue of not being able to retrieve free/busy status from users in Organization B when their mailboxes are located in Exchange Online within the Exchange Hybrid setup. We understand that this is a complex issue, and we are open to any suggestions or recommendations that our readers might have. We will be very thankful for any information to this case, as we strive to resolve this issue and improve our collaboration with Organization B.