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Exchange Server
A family of Microsoft client/server messaging and collaboration software.
1,281 questions
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Hi @Abdul Razzaq ,
Welcome to post our Q&A forum!
It seems that you’re facing issues with your Exchange Delegation Federation certificate. The Federation certificate is used to establish a secure connection between your on-premises Exchange servers and Microsoft’s cloud-based authentication system, which is required for hybrid deployments. The certificate is used for free/busy sharing between your on-premises organization and Exchange Online.
If the Federation certificate has expired, you may need to renew the certificate to resolve the issue. If the certificate has already expired, you will need to remove all federated domains from the federation trust, and then remove and recreate the federation trust.
I have found a similar thread for your reference: https://learn.microsoft.com/en-us/answers/questions/96158/exchange-delegation-federation-certificate-expired
Hope it can help!
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