Please follow these instructions to install your SSL certificate on Microsoft Exchange 2007:
Install the Intermediate Certificate
1. Get your intermediate certificate. Copy and paste the contents into a .crt file by using a text editor software.
2. Launch the Microsoft Management Console (do Start > Run > MMC).
3. Go to File > Add/Remove Snap-in.
4. Click Add. Select Certificates and click Add.
5. Select Computer Account. Click Next and select Local Computer.
6. Click Finish.
7. In the MMC, right-click on Intermediate Certification Authorities and go to All Tasks > Import.
8. Click Browse and select your intermediate certificate (from step 1).
9. Click Next.
Install your SSL Certificate
1. Once you received your SSL certificate by e-mail, please copy and paste it into a text file (with Notepad or Wordpad) and save the file with the .crt extension. (Include the tags -----BEGIN CERTIFICATE----- and -----END CERTIFICATE-----).
2. Copy your .crt file to c:\ on your Exchange Server.
3. Launch the Exchange Management Shell (located in Start > Programs > Microsoft Exchange Server 2007).
4. Run these commands (change the certificate_name.crt):
Import-ExchangeCertificate -Path C:\certificate_name.crt
Enable-ExchangeCertificate -Services "SMTP, IMAP, POP, IIS"
The Services option can be any combination of: IMAP, POP, UM, IIS and SMTP.
5. Check that your certificate is enabled with this command line:
Get-ExchangeCertificate -DomainName yourdomainname
6. In response to the above command, you should see the certificates thumbprint, the list of the services and the name of your certificate file. If your certificate isn't properly enabled, you can re-run the modified Enable command with the certificate thumbprint:
Enable-ExchangeCertificate -Thumbprint [paste thumbprint here] -Services "SMTP, IMAP, POP, IIS" ([thumbprintSSL] must be indicated in square brackets to be taken into accountby your Powershell console)
7. Reboot your server.
8. Test your certificate by connecting with IE, Outlook or ActiveSync.