MSExchange ActiveSync 1100

Hi, @Андрей Михалевский

Thank you for posting your question in the Microsoft Q&A forum.

According to your description, you are encountering an error message that blocks the user's Exchange ActiveSync device request. You can try the following steps to see if they can resolve the issue:

1. Follow the error prompts to check the firewall that filters the request in front of the Client Access server and the Microsoft-Server-ActiveSync virtual directory to see if HTTP OPTIONS method requests are allowed.
2. Try assigning the Exchange Server group to modify the user object permissions to inherit permissions from the object's parent.

• Open Active Directory Users and Computers, go to View > Advanced Features, find the user object and double-click to view the properties.
• Go to Security > Advanced, enable Include inheritable permissions from the parent of this object, and select OK twice.

3. Is your Exchange Server updated with the latest security updates? If not, you can try updating and then connecting.

Refer to: https://zcusa.951200.xyz/en-us/exchange/troubleshoot/client-connectivity/troubleshoot-activesync-with-exchange-server#determine-impact

If you have any questions, please feel free to contact me. If the answer is helpful, please click "Accept Answer" because it can help other members of the Microsoft Q&A community who have encountered similar problems and are looking for solutions. Thank you.

Best,

Jeanne