1. step New-ExchangeCertificate -generaterequest:1 -domainname domain.com,mail.domain.com,smtp.domain.com,pop3.domain.com -privatekeyexportable:1 -path c:\cert.txt -force:1 2. step Import certificate request using web access to your Certification authority - logon as administrator! (WEB SERVER!!!) 3. step Export certificate to a location on the disk… c:\certnew.crt 4. step Import-ExchangeCertificate -path c:\certnew.cer 5. step Enable-ExchangeCertificate -thumbprint 5ACC9A5D90E2CFDBAD6E25CD02362B8954506810 -Services “IIS,POP,SMTP,IMAP” To remove old certificates: Remove-ExchangeCertificate -Thumbprint …………

Read the complete post at http://luka.manojlovic.net/2008/01/12/new-certificate-in-exchange-2007-step-by-step/