Hi,
You can run the following command to check what certificates are available and will expire:
Get-ExchangeCertificate | FL CertificateDomains, Thumbprint, NotBefore, NotAfter, Status
If you found one certificate will expire in one month, you can use new-exchangecertificate cmd-let to generate a new one.
For more information about how to renew the self-signed certificate, please refer to the following article:
Exchange Server 2007: Renewing the self-signed certificate
http://exchangepedia.com/blog/2008/01/exchange-server-2007-renewing-self.html
If anything is unclear, feel free to let me know.
Regards,
Rock Wang
Rock Wang– MSFT