Renew Expired Security Certificate (Exchange 2007)

Get Current Certificate Info

From the Exchange Management Shell

Get the current Certificate:

Get-ExchangeCertificate -domain "MAIL_SERVER_HOSTNAME" | fl

Create a New Certificate

From the Exchange Management Shell

Generate a Certificate with a new expiration date:

Get-ExchangeCertificate -thumbprint "CURRENT_CERT_THUMBPRINT" | New-ExchangeCertificate

If the current Certificate is in use then you will be prompted to overwrite it.

View the new Certificate:

Get-ExchangeCertificate -thumbprint "NEW_CERT_THUMBPRINT" | fl

Enable New Certificate for IIS

From the Exchange Management Shell

Enable-ExchangeCertificate -thumbprint ""NEW_CERT_THUMBPRINT" -services IIS

Delete old Certificate

From the Exchange Management Shell

Remove-ExchangeCertificate -thumbprint "OLD_CERT_THUMBPRINT"

References

http://exchangepedia.com/2008/01/exchange-server-2007-renewing-the-self-signed-certificate.html