MSExchange Web Services 24 and 25 after updating Exchange Certificate

You may receive Event 24 (Expired Certificate) or Event 25 (Certificate Expiring Soon) errors after using the “Add Trusted Certificate Wizard” to install a new Certificate.

The following steps can be used in Exchange Management Shell to manually remove the old certificate.

Get-ExchangeCertificate |FL

Remove-ExchangeCertificate -Thumbprint ‘OldCertificateThumbprint’

Source – Technet